Panel Of Monoclonal Antibodies Research Articles

Simple and rapid flow cytometry assay for the detection of malignant epithelial cells in body fluids.

Morphology is routinely used for detecting malignant cells in body fluids, but it has limitations. Recently, flow cytometry (FCM) is used as an effective tool for studying non-haematological malignancies. The main objective of this study is to standardize a simple and rapid FCM test for the detection of malignant epithelial cells in body fluids. Body fluids that had been processed for cytology/cytology and FCM were enrolled in this prospective study. We developed a fluorescent-labelled, monoclonal antibody panel composed of cell surface markers for this FCM assay. We compared the results of cytology/cell block and FCM. A total of 121 fluid samples were studied. Comparing the diagnostic performance of cytology/cell block and FCM, 52 (43%) cases were positive and 60 (49.5%) cases were negative for carcinoma cells by both techniques. Nine cases showed discordant results between the two techniques. Six cases were cytology+ but FCM- and three cases were FCM+ cytology-. Clustered Epithelial Cell Adhesion Molecule (EpCAM)-positive events with high scatter properties were definitive for positive diagnosis by FCM. We studied PD-L1 expression in 13 cases by FCM. Six cases were reported as false negative by this FCM assay due to hypocellularity and lack of EpCAM expression in malignant cells. This FCM assay is simple, easier and cost-effective yielding sensitive results with no inter-observer variability. FCM would become a valuable tool to complement routine diagnostic cytology and reduces misdiagnosis.

Bispecific antibodies targeting two glycoproteins on SFTSV exhibit synergistic neutralization and protection in a mouse model

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with a high fatality rate of up to 30% caused by SFTS virus (SFTSV). However, no specific vaccine or antiviral therapy has been approved for clinical use. To develop an effective treatment, we isolated a panel of human monoclonal antibodies (mAbs). SF5 and SF83 are two neutralizing mAbs that recognize two viral glycoproteins (Gn and Gc), respectively. We found that their epitopes are closely located, and we then engineered them as several bispecific antibodies (bsAbs). Neutralization and animal experiments indicated that bsAbs display more potent protective effects than the parental mAbs, and the cryoelectron microscopy structure of a bsAb3 Fab-Gn-Gc complex elucidated the mechanism of protection. In vivo virus passage in the presence of antibodies indicated that two bsAbs resulted in less selective pressure and could efficiently bind to all single parental mAb-escape mutants. Furthermore, epitope analysis of the protective mAbs against SFTSV and RVFV indicated that they are all located on the Gn subdomain I, where may be the hot spots in the phleboviruses. Collectively, these data provide potential therapeutic agents and molecular basis for the rational design of vaccines against SFTSV infection.

Comparison of T cell maturation profiles in the 1st and 5th wave of COVID-19 in the Polish population.

The coronavirus pandemic has become the most critical global health threat of this century and the greatest challenge to the human population. The search for simple and quick diagnostic methods enabling the identification of patients infected with the SARS-CoV-2 virus may be a valuable method to track infection. The aim of the study was the clinical and immunological characterization of patients by assessing the degrees of maturity of T lymphocytes from the 1st and 5th waves of coronavirus disease 2019 (COVID-19) in comparison to a healthy control group (HC). We determined leukocyte and T lymphocyte subpopulations (recent thymic emigrant (RTE), naïve, effector, central memory and effector memory) in patients from the 1st COVID-19 wave (n = 23), the 5th COVID-19 wave (n = 38) and HC (n=20) using a panel of monoclonal antibodies using multiparameter flow cytometry. We observed a lower median proportion of lymphocytes and NK cells, and elevated percentage and number of neutrophils in patients from the 5th wave compared to the 1st. We found a reduced percentage of CD4+ effector memory cells in the 1st wave group compared to the 5th wave (14.1 vs 23.2, p < 0.05), and a higher percentage of RTE and naïve CD8+ cells in the 1st wave compared to the 5th wave (p < 0.05). The effector memory CD8+ cells were highest in the 5th wave compared to both 1st wave and HC patients (respectively, 35.1 vs 18.1 vs 19.3%, p < 0.05). The 5th wave group showed significantly more differences compared to HC. Our results showed a clear increase of effector cells with a simultaneous decrease in virgin T cells in the 5th COVID-19 infection. Monitoring lymphocyte subsets during infection allows assessment of the patient's immune status and of readiness of lymphocytes to respond to the immune response, and may be necessary to improve clinical outcomes.

#1896 Monitoring of peripheral blood B cell subsets in long-surviving renal transplant patients

Abstract Background and Aims Studies of peripheral blood B cells subsets in renal transplant patients with operational tolerance off immunosuppressive therapy have identified several differences in B cell subsets. Here we studied B cells in blood lymphocytes from long-surviving renal transplant patients on immunosuppression. Populations of CD4+ T cells, CD8+ T cells, NK cells and B cells, along with subpopulations of B cells, in long-surviving renal transplant recipients were compared to healthy volunteers. We were looking for changes in B cell subsets, which may indicate transplant tolerance and potentially identify patients who could reduce immunosuppression. Method Fresh blood was taken from healthy volunteers (HV) (n = 44) and stable renal transplant patients with grafts surviving &amp;gt;10yrs (RT) (n = 25). T, B, and NK cells were examined using a 6-color TBNK reagent (BD) (CD3/CD4/CD8/CD45/CD19/CD16&amp;CD56). Peripheral blood mononuclear cells were isolated from the remaining fresh blood and were stained with a panel of monoclonal antibodies (CD19/CD21/CD24/CD27/CD38/CD45/IgD/IgM) to identify subpopulations of B cells. Data was acquired on BD FACSCanto II using BD FACSDiva software (v8.0) and analysed using FlowJo. Lymphocyte populations were examined after FSC vs SSC gating and doublets exclusion. Results RT had significantly less lymphocyte counts in comparison to HV (p = 0.0156). There were no significant differences between the CD4+ T cell, CD8+ T cell, or NK cell percentages between RT and HV. B cells were markedly reduced in RT (p = 0.0001) vs HV when examined by TBNK staining. Peripheral blood mononuclear cells of HV (n = 13) and RT (n = 23) stained with a panel of B cell-related antibodies showed CD19+ cells were also significantly reduced in RT (p = 0.0006). There were less CD21hi cells (p = 0.0014) and more CD21lo (p = 0.0014) cells in RT than HV. No differences were seen between the two groups in their proportion of naïve B cells, marginal zone B cells, memory B cells, or class unswitched B cells. However, switched memory B cells were higher in RT than HV (p = 0.0181). Plasmablasts were also higher in RT compared to HV (p = 0.0491). Transitional B cells in RT appeared lower than HV on average, but this did not reach statistical significance (p = 0.1265). The ratio of Treg to B cells, RT (n = 25) showed significantly higher (p = 0.0256) proportions of activated Treg (CD4+CD25+CD127loCD45RA−Foxp3+/hi) to B cells, in comparison to HV (n = 44). There were no significant differences between the two groups in the ratio of naïve Treg (CD4+CD25+CD127loCD45RA+Foxp3+) to naïve T cells (CD4+CD45RA+Foxp3−), or highly activated Treg (CD4+CD25+CD127loCD45RA−Foxp3hi) to activated effector T cells (CD4+CD45RA−Foxp3−). Conclusion B cells were significantly lower in RT compared to HV. There were more plasmablasts and switched memory B cells in RT than HV. The ratio of activated Treg to B cells was higher in RT. This higher proportion of Treg to B cells may be clinically relevant and potentially demonstrate increased immunological suppression in long-surviving renal transplant recipients.

#1167 Examination of subsets of CD4+ lymphocyte subpopulations in long-surviving renal transplant patients

Abstract Background and Aims Subpopulations of CD4+ cells, play a major role in mediation of rejection and tolerance to a renal transplant. This study examined subsets of CD4+ T cells and CD4+CD25+CD127lo Treg in blood of renal graft recipients with grafts surviving &amp;gt;10 years for changes in lymphocyte subpopulations that may indicate transplant tolerance and potentially identify patients who could reduce immunosuppression. Based on CD45RA and CD25/Foxp3 expression, Miyara et al identified five populations (Pop) within CD4+ cells. Pop I, II and III are T regulatory cells (Treg); Pop I as naïve (CD45RA+Foxp3+) Treg, Pop II as activated (CD45RA-Foxp3hi) Treg, and Pop III as cytokine secreting (CD45RA-Foxp3+) cells which also includes activated effector cells. Pop IV are activated T cells (CD45RA-Foxp3−), and Pop V are naïve T cells (CD45RA+Foxp3−). Here, we examined three Treg populations (Pop I-III) within CD4+CD25+CD127lo Treg, and Pop IV and V within CD4+ T cells. To further characterise these subpopulations, we examined chemokine receptor expression (CXCR3, CCR4, CCR6, and CCR7) to identify T helper phenotype (Th-like) of Treg populations. Th1-like Treg were identified as CCR4+CXCR3+CCR6−, Th2-like as CCR4+CXCR3-CCR6−, Th17-like as CCR4+CXCR3-CCR6+, and Th1/Th17-like as CCR4+CXCR3+CCR6+. We also examined expression of activated Treg effector molecules CD39, Class II MHC, and PD-1. Method Peripheral blood mononuclear cells (PBMC) were isolated from fresh blood collected from healthy volunteers (HV) (n = 44) and long-term stable renal transplant patients with grafts surviving &amp;gt;10 yrs (RT) (n = 25). Panels of monoclonal antibodies for Treg (CD4/CD25/CD127/CD45RA/Foxp3), chemokine receptors (CXCR3, CCR4, CCR6, CCR7), and Treg activation and suppression-related molecules (CD39/HLA-DR/PD-1) were also used. Data was acquired on BD FACSCanto II using BD FACSDiva software (v8.0) and analysed using FlowJo. Lymphocyte populations were examined after FSC vs SSC gating and doublets exclusion. T cell and Treg populations were analysed within CD4+ and CD4+CD25+CD127lo T cells. Results RT had lower lymphocyte counts than HV (p = 0.0156) but had a similar percentage of CD4+ T cells. Treg were significantly lower in RT compared to HV (p = 0.0012). RT patients had less naïve Treg (Pop I, p = 0.0083) and naïve effector T cells (Pop V, p = 0.0003), but had higher activated effector T cells (Pop IV, p = 0.0002) than HV. There were no differences in activated Treg Pop II or III between the two groups. There were significantly less cells expressing CXCR3 in RT than HV in Pop I (p = 0.0120), Pop II (p &amp;lt; 0.0001), Pop III (p &amp;lt; 0.0001) and Pop IV (p = 0.0047). Similarly, RT had fewer cells expressing CCR6 compared to HV in Pop II (p = 0.0019), Pop III (p = 0.0015), and Pop V (p = 0.0017). RT had lower proportions of CCR7 expressing cells in Pop I (p = 0.0035), Pop IV (p = 0.0097), and Pop V (p = 0.0002), but higher in Pop II (p = 0.0041) compared to HV. There were similar percentages of cells with Th1 and Th17-like phenotypes in both groups. However, RT had significantly more Th2-like Treg in Pop II (p = 0.0033) and Pop III (p = 0.0100), and significantly less Th1/Th17-like Treg in Pop II (p = 0.0005) and Pop III (p = 0.0017) compared to HV. There were little to no differences in the Treg activation and suppression-related molecules within subpopulations of Treg. Conclusion Long-surviving RT patients had less naïve Treg and naïve effector cells, but increased proportions of activated effector cells. There were little to no differences in the expression of Treg activation or suppression-related molecules in Treg subpopulations. Unexpectedly, activated Treg in RT had significantly higher proportions with a Th2 phenotype and significantly less Treg with a Th1/Th17 phenotype. Whether this is a consequence of immunosuppression, or a biological shift associated with tolerance, remains to be resolved. Further studies are required to investigate the relevance of these changes in identifying induction of transplant tolerance.

A novel LAG3 neutralizing antibody improves cancer immunotherapy by dual inhibition of MHC-II and FGL1 ligand binding

LAG3 is an inhibitory immune checkpoint expressed on activated T and NK cells. Blocking the interaction of LAG3 with its ligands MHC-II and FGL1 renders T cells improved cytotoxicity to cancer cells. Current study generated a panel of LAG3 monoclonal antibodies (mAbs) through immunization of mice followed by phage display. Some of them bound to the D1-D2 domain of LAG3, which is known for the engagement of its ligands FGL1 and MHC-II. Three outperformers, M208, M226, and M234, showed stronger blocking activity than Relatlimab in the FGL1 binding. Furthermore, M234 showed dual inhibition of FGL1 (IC50 of 20.6 nM) and MHC-II binding (IC50 of 6.2 nM) to LAG3. In vitro functional tests showed that M234 significantly stimulated IFN-γ secretion from activated PBMC cells. In vivo studies in a mouse model of hepatocellular carcinoma xenografts demonstrated that combining M234 IgG with GPC3-targeted bispecific antibodies significantly improved efficacy. In addition, GPC3-targeted CAR-T cells secreting IL-21-M234 scFv fusion protein exhibited enhanced activity in inhibiting tumor growth and greatly increased the survival rate of mice. Taken together, M234 has potential in cancer immunotherapy and warrants further clinical trial.

Interaction of heparin with human cardiac troponin complex and its influence on the immunodetection of troponins in human blood samples.

Heparin is a highly charged polysaccharide used as an anticoagulant to prevent blood coagulation in patients with presumed myocardial infarction and to prepare heparin plasma samples for laboratory tests. There are conflicting data regarding the effects of heparin on the measurement of cardiac isoforms of troponin I (cTnI) and troponin T (cTnT), which are used for the immunodiagnosis of acute myocardial infarction. In this study, we investigated the influence of heparin on the immunodetection of human cardiac troponins. Gel filtration (GF) techniques and sandwich fluoroimmunoassay were performed. The regions of сTnI and cTnT that are affected by heparin were investigated with a panel of anti-cTnI and anti-cTnT monoclonal antibodies, specific to different epitopes. Heparin was shown to bind to the human cardiac full-size ternary troponin complex (ITC-complex) and free cTnT, which increased their apparent molecular weights in GF studies. Heparin did not bind to the low molecular weight ITC-complex and to binary cTnI-troponin С complex. We did not detect any sites on cTnI in the ITC-complex that were specifically affected by heparin. In contrast, cTnT regions limited to approximately 69-99, 119-138 and 145-164 amino acid residues (aar) in the ITC-complex and a region that lies approximately between 236 and 255 aar of free cTnT were prone to heparin influence. Heparin binds to the ITC-complex via cTnT, interacting with several sites on the N-terminal and/or central parts of the cTnT molecule, which might influence the immunodetection of analytes in human blood.

A structure-function analysis shows SARS-CoV-2 BA.2.86 balances antibody escape and ACE2 affinity

BA.2.86, a recently described sublineage of SARS-CoV-2 Omicron, contains many mutations in the spikegene. It appears to have originated from BA.2 and is distinct from the XBB variants responsible for many infections in 2023. The global spread and plethora of mutations in BA.2.86 has caused concern that it may possess greater immune-evasive potential, leading to a new wave of infection. Here, we examine the ability of BA.2.86 to evade the antibody response to infection using a panel of vaccinated or naturally infected sera and find that it shows marginally less immune evasion than XBB.1.5. We locate BA.2.86 in the antigenic landscape of recent variants and look at its ability to escape panels of potent monoclonal antibodies generated against contemporary SARS-CoV-2 infections. We demonstrate, andprovide a structural explanation for, increased affinity of BA.2.86 to ACE2, which may increase transmissibility.

Development of Anti-idiotypic Monoclonal Antibody Mimicking SARS-CoV-2 Receptor Binding Domain.

Using the hybridoma technique, we developed a panel of anti-idiotypic monoclonal antibodies (aId-mAb) that mimic The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Receptor-Binding Domain (RBD) molecule against Fragment antigen-binding (Fab) of anti-SARS-CoV-2 (S1, RBD) antibodies. Investigated the in vivo and in vitro effects of these aId-mAbs we developed and examined their antigenic mimicry abilities. Among these 12 antibodies, 6 aId-mAbs (designated FY1B4, FY2A6, H9F3, E6G7, FY7E11, and FY8H3) were selected for further characterization in a series of experiments. First, competitive receptor binding assay results confirmed that six aId-mAbs could specifically bind to the ACE2 receptor in target cells and block the interaction between the RBD molecule and the ACE receptor. Moreover, we examined the immunological activities of these aId-mAbs in female BALB/c and showed that E6G7, H7E11, and H8H3 aId-mAbs induce an antibody response by mimicking RBD and stimulating the immune system. It is considered that these three aId-mAbs will be evaluated as SARS-CoV-2 vaccine candidate molecules in future studies.

Establishment of novel anti-TIM-3 antibodies interfering with its binding to ligands

The T cell immunoglobulin and mucin-domain containing-3 (TIM-3) receptor has gained significant attention as a promising target for cancer immunotherapy. The inhibitory effect of T cells by TIM-3 is mediated through the interaction between TIM-3 and its ligands. Ligand-blocking anti-TIM-3 antibodies possess the potential to reactivate antigen-specific T cells and augment anti-tumor immunity. However, the precise ligand-receptor interactions disrupted by the administration of TIM-3 blocking Abs have yet to be fully elucidated. In this study, we have developed a panel of monoclonal antibodies targeting human TIM-3, namely MsT001, MsT065, MsT229, and MsT286. They exhibited high sensitivities (10 pg/mL) and affinities (3.70 × 10−9 to 4.61 × 10−11 M) for TIM-3. The TIM-3 antibodies recognized distinct epitopes, including linear epitopes (MsT001 and MsT065), and a conformational epitope (MsT229 and MsT286). Additionally, the MsT229 and MsT286 displayed reactivity towards cynomolgus TIM-3. The interactions between TIM-3/Gal-9, TIM-3/HMGB-1, and TIM-3/CEACAM-1 disrupt the binding of MsT229 and MsT286, while leaving the binding of MsT001 and MsT065 unaffected. The inhibitory effect on the interaction between Gal-9 and TIM-3 was found to be dose-dependently in the presence of either MsT229 or MsT286. The findings suggested that the involvement of conformational epitopes in TIM-3 is crucial for its interaction with ligands, and we successfully generated novel anti-TIM-3 Abs that exhibit inhibitory potential. In conclusion, our finding offers valuable insights -on the comprehension and targeting of human TIM-3.

Single-domain antibodies reveal unique borrelicidal epitopes on the Lyme disease vaccine antigen, outer surface protein A (OspA).

Camelid-derived, single-domain antibodies (VHHs) have proven to be extremely powerful tools in defining the antigenic landscape of immunologically heterogeneous surface proteins. In this report, we generated a phage-displayed VHH library directed against the candidate Lyme disease vaccine antigen, outer surface protein A (OspA). Two alpacas were immunized with recombinant OspA serotype 1 from Borrelia burgdorferi sensu stricto strain B31, in combination with the canine vaccine RECOMBITEK Lyme containing lipidated OspA. The phage library was subjected to two rounds of affinity enrichment ("panning") against recombinant OspA, yielding 21 unique VHHs within two epitope bins, as determined through competition enzyme linked immunosorbent assays (ELISAs) with a panel of OspA-specific human monoclonal antibodies. Epitope refinement was conducted by hydrogen exchange-mass spectrometry. Six of the monovalent VHHs were expressed as human IgG1-Fc fusion proteins and shown to have functional properties associated with protective human monoclonal antibodies, including B. burgdorferi agglutination, outer membrane damage, and complement-dependent borreliacidal activity. The VHHs displayed unique reactivity profiles with the seven OspA serotypes associated with B. burgdorferi genospecies in the United States and Europe consistent with there being unique epitopes across OspA serotypes that should be considered when designing and evaluating multivalent Lyme disease vaccines.

Antigenic commonality and divergence of hemagglutinin-esterase-fusion protein among influenza D virus lineages revealed using epitope mapping.

Influenza D virus (IDV) is one of the causative agents of bovine respiratory disease complex, which is the most common and economically burdensome disease affecting the cattle industry, and the need for an IDV vaccine has been proposed to enhance disease control. IDVs are classified into five genetic lineages based on the coding sequences of the hemagglutinin-esterase-fusion (HEF) protein, an envelope glycoprotein, which is the main target of protective antibodies against IDV infection. Herein, we prepared a panel of monoclonal antibodies (mAbs) against the HEF protein of viruses of various lineages to investigate the antigenic characteristics of IDVs and found that the mAbs could be largely separated into three groups. The first, second, and third groups demonstrated lineage-specific reactivity, cross-reactivity to viruses of multiple but not all lineages, and cross-reactivity to viruses of all lineages, respectively. Analyzing the escape mutant viruses from virus-neutralizing mAbs revealed that the receptor-binding region of the HEF molecule harbors virus-neutralizing epitopes that are conserved across multiple lineage viruses. In contrast, the apex region of the molecule possessed epitopes unique to each lineage virus. Furthermore, reverse genetics-generated recombinant viruses with point mutations revealed that amino acids within positions 210-214 of the HEF protein determined the antigenic specificity of each lineage virus. Taken together, this study reveals considerable antigenic variation among IDV lineages, although they are presumed to form a single serotype in terms of HEF antigenicity. Characterization of the antigenic epitope structure of HEF may contribute to selecting and creating effective vaccine viruses against IDV.IMPORTANCEInfluenza D viruses (IDVs) are suggested to create cross-reactive single serotypes in hemagglutinin-esterase-fusion (HEF) antigenicity, as indicated by serological analyses among distinct HEF lineage viruses. This is supported by the high identities of HEF gene sequences among strains, unlike the hemagglutinin (HA) genes of the influenza A virus that exhibit HA subtypes. Herein, we analyzed HEF antigenicity using a monoclonal antibody panel prepared from several virus lineages and found the existence of lineage-conserved and lineage-specific epitopes in HEF molecules. These findings confirm the HEF commonality and divergence among IDVs and provide useful information for constructing a vaccine containing a recombinant IDV virus with an engineered HEF gene, thereby leading to broad immunogenicity.

Retroperitoneal synovial sarcoma

Synovial sarcoma of the retroperitoneum is a rare and aggressive tumor. In some cases, differential diagnosis between retroperitoneal sarcoma and adrenocortical cancer is difficult due to the similar clinical and intrascopic manifestations of these neoplasms. The final diagnosis is established based on the results of histological, immunohistochemical and genetic studies. The most important step in the treatment of synovial sarcoma is complete removal of the tumor. However, despite the radical nature of the intervention, the incidence of local relapse and metastasis remains high.&#x0D; AIM: to conduct a retrospective analysis of the parameters of operated patients with synovial sarcoma of the retroperitoneum.&#x0D; This study is aimed at studying the results of examination and surgical treatment of patients with synovial sarcoma of the retroperitoneal space who were hospitalized in the E.E. Eichwald Clinic surgical department of the North-Western State Medical University named after. I.I. Mechnikov.&#x0D; The patients were assessed for hormonal status using an immunoassay to determine the levels of adrenocorticotropic hormone, cortisol, aldosterone, renin, normetanephrine and metanephrine in the blood, and a dexamethasone suppression test has been performed at a dose of 1 mg. High-performance liquid chromatography has determined 6 glucocorticoids in the blood serum: cortisol, cortisone, corticosterone, 11-deoxycorticosterone, 11-dehydrocorticosterone, 11-deoxycortisol. The urine steroid profile was studied in all the patients using gas chromatography-mass spectrometry. All the patients underwent computed tomography of the abdominal organs and retroperitoneal space with contrast, morphological and immunohistochemical examination of the removed material. The material was fixed in 10% neutral buffered formalin. The pieces were then subjected to standard wiring followed by embedding in paraffin. Sections 2–3 microns thick were prepared from the resulting blocks and stained with hematoxylin and eosin. Immunohistochemical studies were performed on paraffin sections. A panel of monoclonal antibodies was used: protein S-100 (poly), pancytokeratin (AE1/AE3), EMA, cytokeratin-8, -18, chromogranin A, synaptophysin, α-inhibin, SOX-10, CD99, TLE-1, bcl- 2, GATA-3. Postoperative outcomes and follow-up were assessed according to the information in the medical records and data obtained from a telephone conversation with each patient. Statistical processing of the results has not been out due to rare cases of the disease.

Antibody inhibition of influenza A virus assembly and release.

Antibodies are frontline defenders against influenza virus infection, providing protection through multiple complementary mechanisms. Although a subset of monoclonal antibodies (mAbs) has been shown to restrict replication at the level of virus assembly and release, it remains unclear how potent and pervasive this mechanism of protection is, due in part to the challenge of separating this effect from other aspects of antibody function. To address this question, we developed imaging-based assays to determine how effectively a broad range of mAbs against the IAV surface proteins can specifically restrict viral egress. We find that classically neutralizing antibodies against hemagglutinin are broadly multifunctional, inhibiting virus assembly and release at concentrations 1-20-fold higher than the concentrations at which they inhibit viral entry. These antibodies are also capable of altering the morphological features of shed virions, reducing the proportion of filamentous particles. We find that antibodies against neuraminidase and M2 also restrict viral egress and that inhibition by anti-neuraminidase mAbs is only partly attributable to a loss in enzymatic activity. In all cases, antigen crosslinking-either on the surface of the infected cell, between the viral and cell membrane, or both-plays a critical role in inhibition, and we are able to distinguish between these modes experimentally and through a structure-based computational model. Together, these results provide a framework for dissecting antibody multifunctionality that could help guide the development of improved therapeutic antibodies or vaccines and that can be extended to other viral families and antibody isotypes.IMPORTANCEAntibodies against influenza A virus provide multifaceted protection against infection. Although sensitive and quantitative assays are widely used to measure inhibition of viral attachment and entry, the ability of diverse antibodies to inhibit viral egress is less clear. We address this challenge by developing an imaging-based approach to measure antibody inhibition of virus release across a panel of monoclonal antibodies targeting the influenza A virus surface proteins. Using this approach, we find that inhibition of viral egress is common and can have similar potency to the ability of an antibody to inhibit viral entry. Insights into this understudied aspect of antibody function may help guide the development of improved countermeasures.

Generation and Characterization of a Multi-Functional Panel of Monoclonal Antibodies for SARS-CoV-2 Research and Treatment.

The Coronavirus disease 2019 (COVID-19) pandemic caused by Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) is an ongoing threat to global public health. To this end, intense efforts are underway to develop reagents to aid in diagnostics, enhance preventative measures, and provide therapeutics for managing COVID-19. The recent emergence of SARS-CoV-2 Omicron variants with enhanced transmissibility, altered antigenicity, and significant escape of existing monoclonal antibodies and vaccines underlines the importance of the continued development of such agents. The SARS-CoV-2 spike protein and its receptor binding domain (RBD) are critical to viral attachment and host cell entry and are primary targets for antibodies elicited from both vaccination and natural infection. In this study, mice were immunized with two synthetic peptides (Pep 1 and Pep 2) within the RBD of the original Wuhan SARS-CoV-2, as well as the whole RBD as a recombinant protein (rRBD). Hybridomas were generated, and a panel of three monoclonal antibodies, mAb CU-P1-1 against Pep 1, mAb CU-P2-20 against Pep 2, and mAb CU-28-24 against rRBD, was generated and further characterized. These mAbs were shown by ELISA to be specific for each immunogen/antigen. Monoclonal antibody CU-P1-1 has limited applicability other than in ELISA approaches and basic immunoblotting. Monoclonal antibody CU-P2-20 is shown to be favorable for ELISA, immunoblotting, and immunohistochemistry (IHC), however, not live virus neutralization. In contrast, mAb CU-28-24 is most effective at live virus neutralization as well as ELISA and IHC. Moreover, mAb CU-28-24 is active against rRBD proteins from Omicron variants BA.2 and BA.4.5 as determined by ELISA, suggesting this mAb may neutralize live virus of these variants. Each of the immunoglobulin genes has been sequenced using Next Generation Sequencing, which allows the expression of respective recombinant proteins, thereby eliminating the need for long-term hybridoma maintenance. The synthetic peptides and hybridomas/mAbs and quantitative antigen-binding data are under the intellectual property management of the Clemson University Research Foundation, and the three CDRs have been submitted as an invention disclosure for further patenting and commercialization.

Characterization of a Panel of Monoclonal Antibodies Targeting the F-Protein of the Respiratory Syncytial Virus (RSV) for the Typing of Contemporary Circulating Strains.

Respiratory syncytial virus (RSV) is the most common cause of upper and lower respiratory tract infections in infants and young children. Virus-specific monoclonal antibodies (mAbs) can be used for diagnosis, prophylaxis, and research of RSV pathogenesis. A panel of 16 anti-RSV mAbs was obtained from mice immunized by RSV strain Long. Half of them had virus-neutralizing activity. According to Western blot all of these mAbs effectively bound native oligomeric (homodimeric and homotrimeric) forms of the RSV fusion (F) protein. Only five of the mAbs interacted with the monomeric form, and only one of these possessed neutralizing activity. None of these mAbs, nor the commercial humanized neutralizing mAb palivizumab, reacted with the denaturated F protein. Thus, interaction of all these mAbs with F protein had clear conformational dependence. Competitive ELISA and neutralization assays allowed the identification of nine antigenic target sites for the interaction of mAb with the F protein. Five partially overlapping sites may represent a complex spatial structure of one antigenic determinant, including one neutralizing and four non-neutralizing epitopes. Four sites (three neutralizing and one non-neutralizing) were found to be distinct. As a result of virus cultivation RSV-A, strain Long, in the presence of a large amount of one of the neutralizing mAbs, an escape mutant with a substitution, N240S, in the F protein, was obtained. Thus, it was shown for the first time that position 240 is critical for the protective effect of an anti-RSV antibody. To assess the ability of these mAbs to interact with modern RSV strains circulating in St. Petersburg (Russia) between 2014 and 2022, 73 RSV-A and 22 RSV-B isolates were analyzed. Six mAbs were directed to conserved epitopes of the F protein as they interacted most efficiently with both RSV subtypes in a fixed cell-ELISA and could be used for diagnostic assays detecting RSV.

Immunophenotypic Profile of Chronic Lymphoproliferative Diseases in the State of Rio Grande Do Norte, Northeast, Brazil

INTRODUCTION: Chronic lymphoproliferative diseases (CLPD) are considered as a heterogeneous group of diseases characterized by monoclonal expansion and accumulation of apparently mature lymphocytes, which have a proliferative and/or survival advantage over normal lymphocytes in different organs such as bone marrow, peripheral blood and lymph nodes. This translates into the progressive accumulation of clonal cells and their products, causing peripheral blood and bone marrow lymphocytosis, in addition to lymphadenopathy, splenomegaly or other organomegaly. According to the World Health Organization, which reflects the international consensus and is based on pathological, genetic and clinical factors, lymphoproliferative neoplasms are classified according to the stage of maturation and the lineage where the neoplastic transformation occurs through flow cytometry (FC). OBJECTIVES: The aim of this study was to demonstrate the immunophenotypic diagnostic profiles of patients with CLPD in Rio Grande do Norte, Brazil by FC. METHODOLOGY: Were investigated 884 patients with CLPD of both sexes through CF with a panel of monoclonal antibodies directed to CLPD. In addition, other patient information, such as age, gender, and clinical and hematological data were also collected. RESULTS: The results showed that 89.7% of the cases were B Cell CLPD (B-CLPD) and 10.3% T and natural killer cells (T/NK-CLPD). The distribution of B-CLPD cases were as follows: 487 Chronic lymphocytic leukemia; 18 B-Cell Pro-lymphocytic leukemia; 25 Hairy cell leukemia; 6 variant Hairy cell leukemia; 6 Follicular lymphoma leukemized; 4 Splenic lymphoma with villous lymphocytes; 33 Mantle cell lymphoma; 4 Waldenstrom's macroglobulinemia; 69 Multiple myeloma; 14 Plasma cell leukemia; 11 Burkitt's lymphoma and 117 Leukemic Non-Hodgkin lymphoma (Table 1). The distribution of CLPD-T/NK was as follows: 12 Large granular lymphocytic leukemia; 14 T-Cell prolymphocytic leukemia; 18 Adult T-cell leukemia; 20 Sézary syndrome; and 24 Peripheral T-Cell lymphoma and 2 DLPC-NK (Table 1). DISCUSSION: The B-CLPD are the most commonly observed corresponding to more than 85% of all cases and are characterized by the presence of clonal B lymphocytes with expression of a single type of immunoglobulin light chain (kappa or lambda) in a proportion greater than 1/10, associated the strong positivity of Pam-B antigens such as CD19, CD22 and CD20 and the absence or low expression of Pam-T antigens. However, other antigens such as CD200, CD5, FMC7, CD79b and CD103, among others, may be present or absent, specifically characterizing these entities as Chronic lymphocytic leukemia (weak CD22+; CD200+, CD5+, FMC7-, CD79b-), Hairy cells leukemia (strong CD22+; FMC7+; CD79b+; CD5-; CD200-; CD103+; CD123+; CD11c+ and Follicular lymphoma (strongCD22+/CD20+, CD10+, CD200-, CD79B+, FMC7+). T/NK-CLPD are less frequent and are characterized by the expression of Pan-T antigens CD2, CD3, CD5, CD7, CD28 and TCL-1, with clonality evidenced by strong positivity of TCRα/β in most cases and increase of TCD4+ or TCD8+ lymphocytes in a ratio above 1:10 in most cases. In this group, large granular lymphocyte leukemia (LGLG) is a rare type of T/NK cell CLPD characterized by peripheral and medullary infiltration of large hypergranular lymphocytic cells, comprising about 2-5% of all cases, the most commonly seen being CD8+ T cells. CONCLUSION: The results presented demonstrate that immunophenotyping is a defining technique for clarifying the diagnosis of patients with CPLD, clonality was also successfully characterized in the investigated cases of CPLP of B ,T and NK lineages.

Retrospective Immunophenotypic Profile of Acute Leukemias in the State of Rio Grande Do Norte, Northeast, Brazil

INTRODUCTION:The main acute leukemias (ALs) are lymphoid (B or T lineage ALL) and myeloid (AML), in addition to biphenotype AL (BAL) and undifferentiated ALL (IAL), which are rarer. This variation reflects on therapy, requiring methods to characterize these leukemias. Thus, methods such as immunophenotyping by flow cytometry (ICF), multiparametric and quantitative, help in the follow-up of these neoplasms. Objective: The aim of this study was to demonstrate the immunophenotypic diagnostic profiles in patients with AL in Rio Grande do Norte, state, Brazil by FC. Methodology: Bone marrow and peripheral blood samples from 371 patients clinically diagnosed with AL were investigated by CF, using a panel of monoclonal antibodies for the detection of lymphoid (B, T and NK) and myeloid antigens, as well as markers related to cell immaturity such as CD34, Terminal deoxynucleotidyl Transferase (TdT).At the same time, information related to clinical data, age group and sex of patients was also collected. Results: Of all LA investigates 71 were B cell-ALL, 55 T cell-ALL, 239 AML, 04 BAL and 02 IAL. Regarding the immunophenotypic pattern, the main subgroups in relation to age group and were evidenced through the FC. 06/71 were Pro-B ALL, 48/71 Common ALL, 06/71 cyt mü chain ALL and 11/71 mature sIgM+ B-ALL. In B-cell lineage ALL, 51 (71.8%) of the cases were children (less than or equal to 18 years old) and 20 (28.2%) adults (over 18 years old). In T-cell ALL, 9 (16.4%) were pre-T ALL, 12 (21.8%) intermediate ALL and 29 (52.7%) medullary T-type ALL, corresponding to a total of 36.4% children and 63.6% adults. In AML, there was a predominance of involvement in adult patients, corresponding to47 (80.7%) of cases and 192 (80.3%) in children. Biphenotypic and undifferentiated AL were detected in adult patients. DISCUSSION: The B cell-ALL were characterized by natural arrest of B-cells precursors based on the expression of antigens related to this lineage in: i) Pro-B ALL (CD19+, HLA-Dr+, CD34+, TdT+); ii) Common ALL (CD10+, CD19+, cCD79a+, cytCD22+, HLA-Dr+, TdT+/- and CD34+/-); iii) cyt mü chain+ ALL (cyt IgM+, CD19+, HLA-Dr+, cytCD79a+, cytCD22+, CD10-, CD34-) and iv) mature B-ALL (sIgM+, sCD22+, CD10+/-, CD20+ and kappa+ or lambda+). The T-ALL were classified into: i) pre-T-ALL (CD7+, cytCD3+, HLADr+, CD34+ and TdT+), ii) intermediate T-ALL (CD1a+, CD2+, CD7+, cytCD3+, TdT+ and HLADr+, CD4+/CD8+) and Medullary T-ALL (CD4+ or CD8+, sCD3+, CD1a-, TdT+, HLADr+/- and CD34-). It was also possible to observe the aberrant expression of myeloid antigens in B and T-ALL, such as CD13, CD33 and CD66b, mainly related to ALL in the context of KMT2A rearrangement with lineage switching. In addition to transferrin receptors (CD71) and IL-2 receptor (CD25), which have been reported in the context of ALL BCR+/ABL+, as well as the presence of the Philadelphia chromosome. In AMLs, the most observed subtypes were those with little differentiation and with a monocyte component. (CD64+/CD14+). CD15+/CD34+ expression was also observed, indicative of asynchrony of maturation, and phenotypic aberrancy of lymphoid antigens in some cases, predominantly CD7. In addition to other antigens such as CD2 and CD19, CD19 and CD56, In addition, ALL was more frequent in children and males, while AML in adults and females in general, with a predominant incidence in males among adult patient. Conclusion: When properly applied, ICF can have a great impact on the diagnosis, classification and prognostic analysis of neoplastic processes.

Lysosomal Associated Membrane Protein Family Member 5 (LAMP5) As a Novel Mediator of, and Target in High Risk Multiple Myeloma (MM)

Background: Our recently published studies of single cell clonotypic and transcriptional evolution of multiple myeloma precursor disease (Dang et al. Cancer Cell, 2023), as well as related multi-omic studies of more advanced disease, identified a number of genes as potential contributors to progression. Among these is LAMP5, a gene on chromosome 20 that is markedly and specifically overexpressed in the malignant, monoclonal plasma cells in a high proportion of patients. As LAMP5 expression has also been associated with osteolytic bony disease in myeloma, we sought to delineate its potential contributions to the pathobiology of myeloma, which remain incompletely understood. Methods: The impact of LAMP5 knockdown and over-expression was studied using myeloma cell line models both in vitro and in vivo. Moreover, we generated a monoclonal antibody to LAMP5 after finding it was exposed on the myeloma cell plasma membrane, and converted this agent into an antibody drug conjugate (ADC) linked to monomethyl auristatin E (MMAE) or pyrrolobenzodiazepine ( PBD) dimers. Finally, we used the sequence of the single-chain variable fragment to generate LAMP5-targeted chimeric antigen receptor (CAR)-guided T-cells. Results: Analysis of the Multiple Myeloma Research Foundation's CoMMpass SM database indicated that high LAMP5 expression (defined as in the top quartile) in newly diagnosed myeloma patients was significantly associated with markers of increased disease burden, including a higher beta-2-microglobulin (p = 0.047), C-reactive protein (p = 0.0399), serum calcium (p &amp;lt; 0.0001), marrow plasmacytosis (p &amp;lt; 0.001), and a trend towards increased circulating plasma cells (p = 0.075). Moreover, high LAMP5 expression correlated with a shorter progression-free (p = 0.0006) as well as overall survival (p = 0.0006). Similarly, analysis of the University of Arkansas for Medical Sciences gene expression data indicated LAMP5 was increased in the hyperdiploid and proliferative groups that are associated with a poor prognosis. Inducible shRNA-mediated LAMP5 knockdown in myeloma cell lines conferred a survival disadvantage and activated apoptosis. RNA-sequencing analysis identified multiple dysregulated Hallmark pathways, including the G2M checkpoint, the mitotic spindle, apoptosis, mTORC1 signaling, and the unfolded protein response. Proteomic consequences of LAMP5 knockdown included Caspase-7, -8, and -3 cleavage, and increased abundance of Smac, Bim, and PUMA. By contrast, many G2M checkpoint proteins were down-regulated, including Aurora A, Checkpoint-1, Cell division cycle-6, and WEE1 kinases, and decreased levels of phospho-S807/S811 Rb protein were seen. Also, RNA-sequencing revealed mTORC1 pathway dysregulation, and proteomic studies showed decreased activity of AKT and AKT2, mTOR, and p70 S6 kinase. Notably, LAMP5 suppression was associated with reduced levels of expression of an RFP-LC3 fusion protein consistent with a role for LAMP5 in autophagy. In contrast, high LAMP5 expression was associated with improved colony formation in vitro ( A), and promoted disease progression in vivo. Since the LAMP5 promoter had consensus retinoic acid sites, we tested all-trans retinoic acid and found it suppressed LAMP5 protein expression, and reduced in vitro clonogenicity. Finally, since other LAMPs can under some circumstances be found at the plasma membrane, we performed flow and LAMP5 was indeed detected on the surface of unpermeabilized LAMP5-positive myeloma cells. We thus developed a panel of monoclonal antibodies that recognized the extracellular domains of LAMP5, and converted one of these into antibody drug conjugates (ADCs) linked to either MMAE or PBD. Both ADCs reduced the viability of LAMP5-positive myeloma cells in a time- and concentration-dependent manner ( B), activated immunogenic cell death in vitro, and also showed anti-tumor activity in vivo. Importantly, LAMP5-directed CAR T-cells similarly and specifically eliminated only LAMP5-positive myeloma cells with efficacy that was comparable to that of B-cell maturation antigen-targeted CAR T-cells. Conclusions: These pre-clinical in vitro and in vivo data support the possibility that LAMP5 represents a novel mediator of myeloma clonogenicity and high-risk behavior, and that it could serve as a rational therapeutic target leveraging immune therapies that recognize the extracellular domains of cell surface LAMP5.

Centralized MRD Assessment at Early Timepoints in Gimema AML1718 Trial, a Phase 2 Open-Label Study of Venetoclax, Fludarabine, Idarubicin and Cytarabine (V-FLAI) in the Induction Therapy of Non Low-Risk AML

Background: New therapeutic strategies are strongly needed to improve the prognosis of high risk Acute Myeloid Leukemia (AML) patients, such as combination of novel agents and conventional chemotherapy. The Italian GIMEMA AML1718 trial (NCT03455504) investigate the safety and efficacy of the BCL-2 inhibitor venetoclax (VEN) in combination with intensive fludarabine-based induction (FLAI) [fludarabine 30 mg/sqm from day 1 to day 5, cytarabine 2000 mg/sqm from day 1 to day 5, and idarubicin 8 mg/sqm on days 1, 3 and 5] as first-line therapy for newly diagnosed non low-risk ELN AML patients. Results from the Planned Interim Analysis of Safety Run-in and Part 1 (early expansion cohorts) were presented at the last 2022 ASH Meeting. Median overall survival (OS) was not reached; probability of 12-month OS was 76%. Median disease-free survival was not reached. With a median follow-up of 10.5 months, 28 patients (49%) received allogeneic stem cell transplantation (HSCT) in first complete remission (CR). Centralized multicolour flow cytometry minimal residual disease (MFC-MRD) assessment was planned during the phase 2, part 2 of the study (confirmatory cohort) where the lower effective dose of VEN (400 mg/day) was administered in association with FLAI. Here we report results from early time-points (TPs) MRD analysis with the aim of identify the most informative TPs for MRD assessment and prognostic correlations. Methods: Erythrocyte-lysed whole bone marrow (BM) samples obtained at diagnosis from patients enrolled in the confirmatory cohort were centralized and analysed with a broad panel of monoclonal antibodies to identify the leukemia-associated phenotype (LAIP) which was used to track residual leukemic cells during follow-up. Eight color flow cytometry analysis was performed at pre-defined TPs (TP1: post-induction I, TP2: post induction II/consolidation I, following TPs: post consolidation/pre-transplantation) (FACSCantoII; BD Facs Diva Software V6.1.3). A positive flow MRD was defined by the presence of no less than 10 clustered leukemic cells/10^4 total events. Enrollment closed on January 2023. Collection and analysis of later TPs is ongoing. Results: Sixty-seven patients from 11 centers were enrolled in the phase 2, part 2. Risk stratification according to ELN 2017 was intermediate in 46% of patients and high risk in 54%. Fifty-eight/67 patients (87%) obtained CR after induction I. In the centralized MRD analysis, 170 samples has been collected and analysed so far (60 baseline samples, 110 MRD samples). Seven patients lacking baseline sample for LAIP identification were excluded from the analysis. TP1 was available in 57/59 patient achieving CR (97%), and TP2 was available in 29 patients, so far. MFC-MRD negativity was obtained in 31/57 (54%) at TP1 (post V-FLAI, Fig. 1). An increase in MFC-MRD negativity rate was observed at TP2 (post Induction II or consolidation I) with 20 MFC-MRD negative patients/29 available samples (69%, Fig. 1). Thirteen/110 follow up samples (8%), albeit resulting MRD negative, were considered inadequate for the analysis due to haemodilution, 9 from TP1 and 4 from TP2 (Fig. 1). TP1 and TP2 MRD assessment were scheduled at day 28 of Induction I and Induction II/consolidation, respectively. However, in most cases, delayed haematological recovery was observed after V-FLAI, thus resulting in suboptimal samples for MRD evaluation. Conclusions: Preliminary results from centralized MRD analysis confirm that the combination therapy is able to induce high-quality remissions with a very high percentage of MFC-MRD negativity in a difficult cohort of patients, with a higher percentage of MFC-MRD-negative after the completion of the second course of therapy. Delayed haematological recovery may impact on reliability of MRD assessment due to hypocellular and regenerative marrow samples, suggesting that in those cases MRD analysis should be postponed. Correlation with survival will be performed as the data collection will be complete.