Antigen Antibody Research Articles

Analysis of maternal Fc gamma receptor IIIb isoantibodies using immunomagnetic negative selected neutrophils.

The isolation of neutrophils and subsequent detection of anti-human neutrophil antigens (HNA) antibodies are crucial in clinical medicine for the diagnosis of autoimmune neutropenia, neonatal alloimmune neutropenia (NAIN) and transfusion-related acute lung injury (TRALI). This study reports two cases of maternal anti-Fc-gamma-receptor-IIIb (FcγRIIIb) isoimmunization without NAIN symptoms and compares the efficiency of immunomagnetic negative selection (IMNS) with traditional dextran/Ficoll for neutrophil isolation in HNA serological assays. Investigating two cases of maternal anti-FcγRIIIb isoimmunization, neutrophils from three donors were isolated from 8 mL of whole blood using IMNS and dextran/Ficoll. Serological assays included the granulocyte agglutination and immunofluorescence test, monoclonal antibody immobilization of granulocyte antigens and the LABScreen Multi (One Lambda). IMNS and dextran/Ficoll were compared in terms of cell yield, viability, time, cost and purity. Maternal anti-FcγRIIIb isoantibodies with FCGR3B gene deletion were detected in both cases. Newborns and fathers exhibited specific gene combinations: FCGR3B*02/FCGR3B*02 (Case 1) and FCGR3B*02/FCGR3B*03 (Case 2). IMNS outperformed dextran/Ficoll, yielding four times more neutrophils (average neutrophil counts: 18.5 × 103/μL vs. 4.5 × 103/μL), efficiently removing non-neutrophil cells and reducing processing time (30-40 min vs. 70-90 min), although it incurred a higher cost (2.7 times). Two cases of maternal anti-FcγRIIIb isoantibodies, unrelated to NAIN, were identified. Although neutropenia has not been described in these cases, we emphasize the importance of identifying asymptomatic cases with the potential for severe neutropenia. Additionally, IMNS is introduced as a rapid, high-yield, high-purity neutrophil isolation technique, beneficial for serological assays detecting anti-HNA antibodies.

Diagnostic accuracy of DPP Fever Panel II Asia tests for tropical fever diagnosis.

Fever is the most frequent symptom in patients seeking care in South and Southeast Asia. The introduction of rapid diagnostic tests (RDTs) for malaria continues to drive patient management and care. Malaria-negative cases are commonly treated with antibiotics without confirmation of bacteraemia. Conventional laboratory tests for differential diagnosis require skilled staff and appropriate access to healthcare facilities. In addition, introducing single-disease RDTs instead of conventional laboratory tests remains costly. To overcome some of the delivery challenges of multiple separate tests, a multiplexed RDT with the capacity to diagnose a diverse range of tropical fevers would be a cost-effective solution. In this study, a multiplex lateral flow immunoassay (DPP Fever Panel II Assay) that can detect serum immunoglobulin M (IgM) and specific microbial antigens of common fever agents in Asia (Orientia tsutsugamushi, Rickettsia typhi, Leptospira spp., Burkholderia pseudomallei, Dengue virus, Chikungunya virus, and Zika virus), was evaluated. Whole blood (WB) and serum samples from 300 patients with undefined febrile illness (UFI) recruited in Vientiane, Laos PDR were tested using the DPP Fever Panel II, which consists of an Antibody panel and Antigen panel. To compare reader performance, results were recorded using two DPP readers, DPP Micro Reader (Micro Reader 1) and DPP Micro Reader Next Generation (Micro Reader 2). WB and serum samples were run on the same fever panel and read on both micro readers in order to compare results. ROC analysis and equal variance analysis were performed to inform the diagnostic validity of the test compared against the respective reference standards of each fever agent (S1 Table). Overall better AUC values were observed in whole blood results. No significant difference in AUC performance was observed when comparing whole blood and serum sample testing, except for when testing for R. typhi IgM (p = 0.04), Leptospira IgM (p = 0.02), and Dengue IgG (p = 0.03). Linear regression depicted R2 values had ~70% agreement across WB and serum samples, except when testing for leptospirosis and Zika, where the R2 values were 0.37 and 0.47, respectively. No significant difference was observed between the performance of Micro Reader 1 and Micro Reader 2, except when testing for the following pathogens: Zika IgM, Zika IgG, and B pseudomallei CPS Ag. These results demonstrate that the diagnostic accuracy of the DPP Fever Panel II is comparable to that of commonly used RDTs. The optimal cut-off would depend on the use of the test and the desired sensitivity and specificity. Further studies are required to authenticate the use of these cut-offs in other endemic regions. This multiplex RDT offers diagnostic benefits in areas with limited access to healthcare and has the potential to improve field testing capacities. This could improve tropical fever management and reduce the public health burden in endemic low-resource areas.

Retrospective Study of Various Factors In Pediatric To Severe Dengue Infection

Introduction: Dengue epidemics are known to have occurred over the last three centuries in tropical, subtropical and temperate areas of the world. Annually a 100 million cases of Dengue fever and half a million cases of dengue hemorrhagic fever (DHF) occur in the world with a case fatality in Asian countries of 0.5%–3.5%. Objective: To assess the various factors in pediatric to severe dengue infection. Methods: A hospital-based Retrospective study was conducted at Department Of Paediatric, Mugda Medical College Hospital, Dhaka, Bangladesh from October to December 2023. Number of patients included in the study was 50. In children with high degree clinical suspicion of Dengue infection NS 1 antigen (who came within first 48 hours of fever) and/or Dengue antibody IgM, IgG (who came after five days of fever) were performed. Positive Dengue cases were taken written informed consent & interviewed on the risk factors of Dengue infection. Data related to patients demography, risk factors, clinical presentation, pattern of Dengue infection and outcome were documented on the pre-structured questionnaire. Results: The study was enrolled 100 patients of suspected dengue fever of whom 50 (50.0%) were serologically confirmed to have dengue infection. 30 (60%) patients were males and 20 (40%) were females. 38 (76%) patients had classic dengue fever while 12 (24%) fulfilled the criteria of dengue hemorrhagic fever. Of those patients with dengue hemorrhagic fever, 6 patients had developed dengue shock syndrome. Among the study 44 (88%) from urban and 6 (12%) rural area patients. All cases and is the most common symptom followed by headache, myalgia, vomiting etc. Hemorrhagic manifestations were seen that included petechiae, ecchymosis, gum bleeding, hematuria, malena, hematemesis and epistaxis. Most common complicationswere hepatic dysfunction, renal failure, multi organ failure, encephalopathy and ARDS. Among 50 suspected dengue cases 38 (76.0%) cases were serologically dengue positive. Among the 38 serologically dengue positive patients 17 (44.7%) were NS1 antigen positive, 13 (34.2%) IgM antibodies and 8(21.0%) both IgM and IgG antibodies positive. The distribution of the serologically dengue positive patients out of 50 clinically suspected cases. Conclusion: Dengue is one amongst the key causes of dedifferentiated fever. It presents as an extremely broad wellness and is hardly recognized as a clinical entity by primary health care physicians. This study highlights the practician the importance of break bone fever to clinicians within the areas of medical specialty, manifestations, complications and outcome of the wellness

Detection of dengue in German tourists returning from Ibiza, Spain, related to an autochthonous outbreak, August to October 2022.

In February 2023, German public health authorities reported two dengue cases (one confirmed, one probable) and four possible cases who travelled to Ibiza, Spain, in late summer/autumn 2022; the infection was probably acquired through mosquito bites. Case 1 visited Ibiza over 1 week in late August with two familial companions; all three developed symptoms the day after returning home. Only Case 1 was tested; dengue virus (DENV) infection was confirmed by presence of NS1 antigen and IgM antibodies. Case 2 travelled to Ibiza with two familial companions for 1 week in early October, and stayed in the same town as Case 1. Case 2 showed symptoms on the day of return, and the familial companions 1 day before and 3 days after return; Case 2 tested positive for DENV IgM. The most probable source case had symptom onset in mid-August, and travelled to a dengue-endemic country prior to a stay in the same municipality of Ibiza for 20 days, until the end of August. Dengue diagnosis was probable based on positive DENV IgM. Aedes albopictus, a competent vector for dengue, has been present in Ibiza since 2014. This is the first report of a local dengue transmission event on Ibiza.

A novel frameshift mutation in RHAG leads to Rhnull phenotype in a Chinese individual.

We recently encountered a Rhnull phenotype proband within one family in the Chinese population. Rhnull is a rare autosomal recessive disorder characterized by the absence of the Rh antigens on the erythrocyte membrane, resulting in chronic hemolytic anemia. This study described the serological and molecular analysis of a Chinese Rhnull proband and his immediate family. Red blood cells antigen phenotyping and antibody screening/identification were conducted. RHD, RHCE, and RHAG were analyzed using genomic DNA by polymerase chain reaction and sequence analysis. Serologic tests showed a D-C-E-c-e- phenotype in the proband associated with the suspicion of anti-Rh29 (titer 16). Molecular analyses showed a new mutation (c.406dupA) in exon 3 of RHAG. This duplication introduced a reading frameshift (p.Thr136AsnfsTer21). The RHAG mutation was found in the homozygous state for the proband and heterozygous state for his parents. We identified a novel RHAG mutation resulting in the Rhnull phenotype of the regulator type. Inheritance of the novel allele was shown by family study.

Successful Desensitization in a Patient with Donor-Specific Antibodies Persisting after Pretransplant Immunosuppression Using Intravenous Immunoglobulin and Plasma Exchange

The use of posttransplant cyclophosphamide has revolutionized the field of haploidentical hematopoietic stem cell transplant. The impact has been especially enhanced in low- and middle-income countries. Unrelated donor pool in developing nations is often limited due to the lack of large unrelated donor registries. Donor-specific antibodies (DSAs) are preformed immunoglobulin G anti-human leukocyte antigen (HLA) antibodies against HLA antigens that are not shared with the donor. We present successful desensitization in a 13-year-old patient with class III β-thalassemia with very high MFI DSAs with flow crossmatch positivity, persisting after pretransplant immunosuppression.

Application of a Self-Assembly Sensing Layer to Grating Sensor Cabinets for Biomedical Sensing of Rheumatoid Arthritis Antigen–Antibodies

Application of a Self-Assembly Sensing Layer to Grating Sensor Cabinets for Biomedical Sensing of Rheumatoid Arthritis Antigen–Antibodies

Clinical Significance and Remaining Issues of Anti-HBc Antibody and HBV Core-Related Antigen.

Currently, hepatitis B virus (HBV) core antibody (anti-HBc antibody) and HBV core-related antigen (HBcrAg) are widely used as serum markers for diagnosis based on the HBV core region. This review focused on anti-HBc antibodies and HBcrAg and aimed to summarize the clinical significance of currently used assay systems and the issues involved. While anti-HBc is very significant for clinical diagnosis, the clinical significance of quantitative assay of anti-HBc antibody has been reevaluated with improvements in diagnostic performance, including its association with clinical stage and prediction of carcinogenesis and reactivation. In addition, concerning the new HBcrAg, a high-sensitivity assay method has recently been established, and its diagnostic significance, including the prediction of reactivation, is being reevaluated. On the other hand, the quantitative level of anti-HBc antibody expressed in different units among assay systems complicates the interpretation of the results. However, it is difficult to standardize assay systems as they vary in advantages, and caution is needed in interpreting the assay results. In conclusion, with the development of highly sensitive HBcrAg and anti-HBc antibody, a rapid and sensitive detection assay system has been developed and used in clinical practice. In the future, it is hoped that a global standard will be created based on the many clinical findings.

Diagnostic value of IgG antibody and stool antigen tests for chronic Helicobacter pylori infections in Ibb Governorate, Yemen

The stool antigen test (SAT) and the serum Helicobacter pylori (H. pylori) IgG antibody assays exhibit significant utility in the clinical diagnosis of H. pylori infection and in distinguishing between acute and chronic infections. The main objective of the current study was to identify the diagnostic value of serum H. pylori IgG antibody and SAT in the detection of H. pylori infections among chronic H. pylori-infected patients residing in Ibb Governorate, Yemen. 200 patients with H. pylori infection, confirmed through positive results in the serum immunochromatographic antibody test, were selected for H. pylori infection confirmation using serum H. pylori IgG antibodies and SAT across diverse hospitals, gastroenterology, and Hepatology clinics in Ibb Governorate. After the selection of patients, blood and stool specimens were obtained from all participants and underwent analysis via the Statistical Package for the Social Sciences (SPSS). The prevalence of H. pylori infection demonstrated variability based on the confirmatory tests, with rates of 54% for SAT and 78.5% for serum H. pylori IgG antibody, contrasting with a 100% prevalence observed in the screening serum immunochromatographic antibody test. Clinically, the study categorized H. pylori infections into four stages, whereby a significant proportion of patients (40.5%) exhibited positivity for both serum H. pylori IgG antibody and SAT, indicative of active chronic infections. The majority of positive cases only manifested serum H. pylori IgG antibody presence (chronic infections) at 38%, whereas 13.5% exclusively tested positive for SAT, corresponding to acute infections. Moreover, 88% of patients did not have either serum H. pylori IgG antibody or SAT (absence of infections) during confirmatory tests. Noteworthy is the study's approach employing multiple tests for H. pylori infection detection, focusing predominantly on chronic infections-prevailing types caused by H. pylori. The results revealed a significant association between serum levels of H. pylori IgG antibody and SAT results with the presence of diverse gastrointestinal symptoms among patients, which increased with long H. pylori infection durations.

TRBC1-targeting antibody-drug conjugates for the treatment of T cell cancers.

Antibody and chimeric antigen receptor (CAR) T cell-mediated targeted therapies have improved survival in patients with solid and haematologic malignancies1-9. Adults with T cell leukaemias and lymphomas, collectively called T cell cancers, have short survival10,11 and lack such targeted therapies. Thus, T cell cancers particularly warrant the development of CAR T cells and antibodies to improve patient outcomes. Preclinical studies showed that targeting T cell receptor β-chain constant region 1 (TRBC1) can kill cancerous T cells while preserving sufficient healthy T cells to maintain immunity12, making TRBC1 an attractive target to treat T cell cancers. However, the first-in-human clinical trial of anti-TRBC1 CAR T cells reported a low response rate and unexplained loss of anti-TRBC1 CAR T cells13,14. Here we demonstrate that CAR T cells are lost due to killing by the patient's normal T cells, reducing their efficacy. To circumvent this issue, we developed an antibody-drug conjugate that could kill TRBC1+ cancer cells in vitro and cure human T cell cancers in mouse models. The anti-TRBC1 antibody-drug conjugate may provide an optimal format for TRBC1 targeting and produce superior responses in patients with T cell cancers.

AN EVALUATION OF A GOLD SURFACE FUNCTIONALIZATION PROCEDURE FOR ANTIBODY BINDING AND PROTEIN DETECTION USING 11-MERCAPTOUNDECANOIC ACID (11-MUA)

Immunosensors play an essential role in biological element recognition systems. Among the numerous types of electrodes utilized for immunosensor, gold electrodes with surface modification have attracted considerable attention and have experienced various improvements and developments due to their advantages, compromising high conductivity and chemical stability. Self-assembled monolayer (SAM) has been used as an effective approach for biomarker immobilization onto electrodes. In this study, two types of gold electrodes, namely, sputtered gold on a glass slide and screen-printed gold electrodes, were utilized to assess the performance of the proposed procedure utilizing 11-Mercaptoundecanoic acid (11-MUA). Bovine serum albumin–fluorescein isothiocyanate conjugate (BSA-FITC) and anti-albumin antibody (anti-BSA) were employed as the antigen–antibody pair. Microscope-based fluorescent, Raman spectroscopy and electrical measurements, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were conducted to validate the success of each step in the surface functionalization process. The results showed that BSA proteins were immobilized on the modified electrode, as indicated by the fluorescent green color observed under the microscope and the changes in surface impedance recorded in Raman spectroscopy, CV and EIS signal graphs. Additionally, the influence of the 11-MUA incubation time and the protein concentration on the performance of the gold electrode surface functionalization process were investigated. The results indicate that an incubation time exceeding 24 h and a protein concentration of 5 [Formula: see text]M was found to be the most optimal conditions. The screen-printed gold electrode exhibited a slightly superior performance in comparison to the sputtered gold electrode. This work has verified the proposed gold surface functionalization process and can serve as a solid foundation for future immunosensor research studies.

A novel immunocomplex capture fluorescence assay (ICFA) using fluorescent beads and transfected cells for specific identification of human neutrophil antigen (HNA)-1a and -1b antibodies.

To identify specific human neutrophil antigen (HNA) antibodies, assays using neutrophils such as monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) are recommended. However, these assays are limited by labor-intensive neutrophil preparation and varying antigen expression levels. We evaluated a newly developed immunocomplex capture fluorescence assay (ICFA) for identifying HNA-1 antibodies and compared it to MAIGA and LABScreen Multi (LABM), which utilizes recombinant HNA-coated Luminex beads. For ICFA, HNA-1a or HNA-1b transfected cells replaced neutrophils. Cells incubated with serum were lysed, and immune complexes were captured using five CD16 monoclonal antibody-conjugated Luminex beads. Nine antisera with known specificity and 26 samples suspected of containing HNA antibodies were analyzed by ICFA and MAIGA using neutrophils or transfected cells (ICFA-N or ICFA-T, and MAIGA-N or MAIGA-T, respectively). ICFA-T and MAIGA-N accurately determined the specificity of all antibodies in the nine antiserum samples. The ICFA-T detection limit was 2048-fold for anti-HNA-1a and 256-fold for anti-HNA-1b; the limits of MAIGA-T, MAIGA-N, and LABM were 32-, 4 ~ 64-, and 128-fold for anti-HNA-1a and 64-, 16 ~ 64-, and 32-fold for anti-HNA-1b, respectively. Twelve and 7 of the remaining 26 samples tested negative and positive, respectively, in both ICFA-T and MAIGA-N. Antibody specificity against HNA-1a or HNA-1b determined using ICFA-T agreed with that determined using MAIGA-N and LABM. Another seven samples tested positive in ICFA-T but negative in MAIGA-N. The novel ICFA is highly sensitive and exhibits specificity similar to MAIGA and LABM for detecting HNA-1 antibodies.

Abstract 2479: Discovery of agonist CD28-specific single domain antibodies from alpaca

Abstract Upon immune activation, in addition to the first signal driven by the TCR-peptide/MHC interactions, the costimulatory signals are indispensable to optimal T-cell activation, the absence of which will trigger naive T cells to an anergic state. The CD28-CD80/CD86 pathway is widely known as the most classical and critical costimulatory signal for the initial activation of T cells. Bispecific T-cell engagers targeting CD3e can activate cytotoxic T-cells and have shown remarkable tumor regressions in clinical trials. However, the absence of a costimulatory signal through CD28 results in insufficient T-cell activation and early exhaustion. Combination of both CD3e and CD28 targeting antibodies offers attractive approach to optimally boost T-cell activity. Development of superagonistic CD28-targeting antibody has been paused after TeGenero‘s TGN1412 Phase 1 trial in 2006 due to life-threatening cytokine release syndrome. Unlike superagonist TGN1412, which activates T cells and induce cytokine storm, tumor targeting antigen and cross-linking dependent CD28 bispecific antibody is supposed to display little or no toxicity. In the present study, we explored Alpaca immunized phage library approach to generate cross-linking dependent agonist CD28 single domain antibody for bispecific antibody development. Alpacas were immunized subsequently with recombinant human CD28 extracellular domain and 293F cells stably expressing human CD28. Serum samples after immunizations showed decent immune response against CD28. At the end of Boost 2 and 3, peripheral blood was collected and phage display libraries were constructed using VHH specific primers. Phage display libraries were panned against recombinant CD28 ECD protein and CHOK1 cells overexpressing CD28. After one round of panning, both protein and cell panning tracks showed robust enrichment in output titer and repeating sequences. Next, 600 clones were randomly picked for screening by the binding to U266B1 cells endogenously expressing CD28. Of the 326 clones showed positive binding to U266B1, 79 unique sequences were identified. Secondary screening by ELISA and FACS using periplasmic extract confirmed 69 unique sequences that bound to both CD28 protein and cells expressing CD28. Seventeen unique sequences were selected for VHH-Fc production. All purified VHH-Fc showed sub-nanomolar affinity by ELISA and bind to primary T cells by flow cytometry. Three VHH-Fc induced IL-2 production in a primary T cells activation assay only when cross-linked and in the presence of CD3 co-stimulation and are suitable for further bispecific T cell engager development. Citation Format: Yunyun Chen, Yannan Ding, Xiaoyan Liu, Qianqian Zhu, Wenfang Xin, Hu Liu, Teddy Yang, Yikai Qiu. Discovery of agonist CD28-specific single domain antibodies from alpaca [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2479.

Comparison of B cells' immune response induced by PEDV virulent and attenuated strains.

Porcine epidemic diarrhea virus (PEDV) is an acute, highly contagious enterovirus that infects pigs of all ages. The B cells are important for antigen presentation, antibody production, and cytokine secretion to resist infection. However, the role of B cells in PEDV infection remains unclear. In this study, the effects of PEDV virulent (QY2016) and attenuated strains (CV777) on B cells sorted from neonatal piglets, nursery piglets, and gilts were investigated. The results showed that PEDV-QY2016 and PEDV-CV777 could significantly increase the expression of CD54 and CD27 in B cells from neonatal piglets. The percentages of CD80, MHC II, and IgM expressed on neonatal piglet B cells infected with PEDV-QY2016 were significantly lower than those expressed on the B cells infected with PEDV-CV777. Both PEDV-QY2016 and PEDV-CV777 could stimulate IFN-α and GM-CSF secretions in neonatal piglet B cells; IL-1, IFN-α, and IL-4 secretion in nursery piglet B cells; and IL-1, TGF-β secretion, and GM-CSF in gilt B cells. Furthermore, both PEDV-QY2016 and PEDV-CV777 could induce the secretion of IgA, IgM, and IgG in nursery piglet B cells but could not induce the secretion of IgA, IgM, and IgG in neonatal piglet B cells. The secretion of IgA, IgM, and IgG was significantly higher by the PEDV-CV777 strains infected B cells than those by the PEDV-QY2016 strains infected gilt B cells. In conclusion, the surface molecule expression, cytokine secretion, and antibody production of B cells induced by PEDV are closely related to the ages of pigs and the virulence of the PEDV strain.

Abstract 5805: A novel platform of diversified payloads to drive ADC innovation

Abstract First generation of antibody drug conjugates (ADCs) for anticancer therapy has been described more than two decades ago with gemtuzumab-ozogamicin receiving the first approval in 2000. Over the last 4 years, 8 new ADCs got FDA approval essentially due to the innovation on the linker improving the disposition in patients and the manufacturability together with the technical advantages in the engineering of biologics and the introduction of new cytotoxic payloads such as deruxtecan. In the future, next generation ADCs will be developed exploring payloads beyond the currently used cytotoxins to improve safety, efficacy and durability of responses and therefore the short- and long-term therapeutic benefit to patients. Nerviano Medical Sciences (NMS) generated a portfolio of novel and diversified payload linkers leveraging on its proprietary chemical collection that includes cytotoxic and targeted payloads. A rigorous screening funnel has been applied considering diversification in terms of MoAs, pharmacokinetic properties, mechanism of resistance and combinability with other therapies to identify the optimal match with specific tumor types and targets, generating a new class of ADCs with improved selectivity and efficacy for hard-to-treat cancers even in chemoresistant settings. NMS ADC platform incorporates 1) our patent protected payload linker NMS-P945, a duocarmycin like DNA minor groove binder and alkylating agent inducing DNA damage, acting in chemoresistant cells with bystander effect and immunogenic cell death properties and generating ADCs highly efficacious in mouse xenograft models and safe when administered in NHP, 2) novel anthracyclines (PNU-682 derivatives) with an improved stability and safety profile and 3) targeted molecules with different mechanism of action including payloads active in synthetic lethality contexts. Payload linkers with different functionalization generated from each payload have been evaluated for chemical stability, sensitivity to lysosomal protease cleavage, and conjugability to monoclonal antibodies. The ADCs, generated with proof-of-concept antibodies (e.g. Trastuzumab), were characterized in terms of Drug to Antibody Ratio (DAR), aggregation level, plasma stability, antigen binding and differential antiproliferative activity in target positive vs target negative tumor cells. The best products resulting from the screening funnel have been subjected to a multidimensional analysis taking into consideration payload properties, tumor features and antigen expression in selected populations with the aim of identifying tumor types particularly sensitive to the payload. Our multidimensional approach coupling new payload linker with innovative MoA to careful selection of patients will allow to reach unprecedented efficacy and safety profile. Citation Format: Paolo Orsini, Matteo Salsa, Simona Rizzi, Ulisse Cucchi, Daniela Faiardi, Alessia Burocchi, Antonella Ciavolella, Rosita Lupi, Fabio Gasparri, Barbara Valsasina. A novel platform of diversified payloads to drive ADC innovation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5805.

Assessing Immunity to Hepatitis A and Hepatitis B Among Individuals in Custody Living With HIV.

Screening upon entry into prison for hepatitis A virus (HAV) and hepatitis B virus (HBV) provides an ideal public health opportunity to offer vaccination to individuals who are nonimmune. We conducted a retrospective review of HAV and HBV immunity among adults living with HIV in the Illinois Department of Corrections between January 1, 2019, and December 31, 2019. The primary objective was to assess rates of HAV and/or HBV immunity in individuals with HIV. In total, 436 people were included in the study. Of 425 patients who had data for HAV vaccination, 335 were immune. Of 421 patients who had data for HBV vaccination, 272 were immune. Of the 149 patients who were nonimmune to HBV, 22 had active HBV and 6 had an equivocal HBV surface antibody and negative HBV surface antigen. In total, 212 (52%) were immune to both HAV and HBV, and 31 (8%) had no immunity to either HAV or HBV. These data demonstrate an important opportunity to discuss and provide vaccination while in custody.

Abstract 4808: Small intestinal leiomyosarcoma in a young adult

Abstract Objectives: • Outline the epidemiology of leiomyosarcoma•Identify the immunohistochemistry of a leiomyosarcoma Introduction: Primary small intestinal malignancies are rare malignancies as compared with other malignancies of the gastrointestinal tract. Here, we present a case of a jejunal leiomyosarcoma in a young adult. Case Presentation: A 23-year-old Caucasian male with GERD presented with five months of abdominal pain, intermittent nausea with non-bloody emesis, and a 20-pound weight loss. Presenting vital signs were within normal limits. Physical exam revealed conjunctival pallor with epigastric tenderness to palpation. Serology demonstrated iron deficiency anemia, hemoccult positive stool, negative CEA, CA19-9, and AFP tumor markers. HIV antigen antibody and EBV-PCR were non-reactive. CT of the abdomen and pelvis revealed markedly thickened heterogenous jejunal loop in the left hemiabdomen with associated mesenteric adenopathy and small volume pelvic ascites. EGD with push enteroscopy revealed a single, malignant appearing and ulcerated mass in the proximal jejunum. PET-CT showed a hypermetabolic, multilobulated, ill-defined mass involving multiple loops of jejunum. He underwent exploratory laparotomy with resection of a proximal jejunal mass (10x8 x7 cm), mesenteric lymphadenectomy, and a jejunojejunostomy creation. Pathology demonstrated leiomyosarcoma (pT2aN0MoG3), and he was initiated on cyclophosphamide and doxorubicin. Discussion: Primary small intestinal malignancies are rare malignancies with an incidence of less than 5% of all GI malignancies. 56 cases of GI leiomyosarcoma in adults were identified between 2000-2012 with a peak incidence between 55-59 years of age (Aggarrwal 2012). Leiomyosarcomas are soft tissue sarcomas arising from bones, tendons, blood vessels, or muscles with a spectrum of disease ranging from low-grade cutaneous lesions to aggressive lesions of internal organs with significant potential for metastasis (Pipe 2002). Diagnosis is based on immunohistochemical positivity for SMA, desmin, and h-caldesmon, and negativity for CD117, CD34, and DOG1.1, notably lacking KIT and PDGFRA mutations (Aggarwal 2012). Treatment involves surgical resection and a cost benefit analysis of adjuvant chemotherapy with (Reynolds, 2014). This case of a 23 year old, without significant risk factors, diagnosed with a jejunal leiomyosarcoma presents as one of the youngest cases ever to be reported and emphasizes the importance of recognizing the cancer in a broader range of the adult population. Citation Format: Alyssa A. Guo, Blake H. Bentley, Abigail L. Ellington, Haiyan Lu, William C. Lippert. Small intestinal leiomyosarcoma in a young adult [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4808.

Effect of sirolimus combined with anti-CD20 monoclonal antibody desensitization on the prognosis of patients underwent haploidentical stem cell transplantation

Objective: To investigate the effects of sirolimus combined with anti-CD20 monoclonal antibody desensitization on the prognosis of patients with haploidentical stem cell transplantation (haplo-SCT). Methods: Fifteen consecutive patients who received haplo-SCT and pre-transplant donor specific anti-human leukocyte antigen (HLA) antibody (DSA) positive [mean fluorescence intensity (MFI)≥2 000] in the Institute of Hematological Diseases from November 2021 to March 2023 were retrospectively recruited into the desensitized group. There were 4 males and 11 females, with a median age [M(Q1, Q3)] of 48 (37, 59) years. All patients were desensitized with sirolimus combined with anti-CD20 monoclonal antibody. The non-desensitized group included 29 patients with haplo-SCT who had not received desensitization treatment from August 2012 to June 2016. There were 12 males and 17 females with a median age of 42 (26, 50) years. Up to October 1, 2023, the median follow-up time was 13 (9, 18) months in the study group and 23 (14, 29) months in the control group. The changes of MFI before and after desensitization treatment and the prognosis of patients in the desensitized group were compared, including the incidence of primary implantation failure (pGF), neutrophil implantation time, platelet implantation time, grade Ⅱ-Ⅳ acute graft-versus-host disease (GVHD) and chronic GVHD incidence, non-recurrence related mortality, event-free survival rate, disease-free survival rate and overall survival rate. The survival curve was drawn by Kaplan-Meier method, and the survival rate between groups was compared with Log-rank test. Results: After desensitization treatment, the level of DSA MFI in the desensitized group decreased from 8 879 (7 544, 11 495) to 3 781 (1 638, 4 165) after desensitization treatment (P<0.01). All of the patients achieved hematopoietic recovery, and the median time for neutrophil and platelet engraftment were 14 (11, 15) and 20 (18, 25) days, respectively. The incidence of pGF in the desensitized group was 0, which was lower than that in the non-desensitized group (34.5%, 10/29) (P=0.011). The expected 1-year disease-free survival rate and overall survival rate in the desensitized group were 100% (15/15) and 100% (15/15) respectively, while those in the non-desensitized group were 75.9% (22/29) and 75.9% (22/29) respectively, the difference was not statistically significant (both P>0.05). The one-year event-free survival rate in the desensitized group was expected to be 100% (15/15), which was higher than that in the non-desensitized group (51.3%, 15/29) (P=0.002). Conclusion: Sirolimus combined with anti-CD20 monoclonal antibody desensitization therapy can reduce the DSA level of haplo-SCT recipients, promote hematopoietic engraftment after transplantation, and avoid the occurrence of pGF after transplantation.

Analysis of transfusion effect of different platelet matching schemes in patients with platelet transfusion refractoriness

Objective: To analyze the transfusion effect of different platelet matching schemes in patients with platelet transfusion refractoriness (PTR). Methods: A total of 94 patients with PTR received by Taiyuan Blood Center from January to December 2021 were retrospectively analyzed, including 26 males and 68 females, aged 53(34,66) years. Platelet antibody screening was performed by enzyme-linked immunosorbent assay (ELISA). For patients with positive human leukocyte antigen (HLA) class Ⅰ antibodies, Luminex platform liquid chip assay was used to identify the specificity of antibodies, and platelets with missing allelic expression antigen corresponding to their specific antibodies were found in the platelet donor gene database established in our laboratory. For patients with negative class HLA-Ⅰ antibody screening, medium and high-resolution HLA-A and B alleles were genotyped by polymerase chain reaction restriction sequence specific oligonucleotide (PCR-SSO), and the compatible platelets were searched from the platelet donor gene database by HLA cross-reactive group genotype matching scheme or directly selected by serological cross-matching. The PCI compliance rate and total transfusion effective rate of different mismatch site groups and different matching scheme groups were statistically analyzed. Results: Platelet antibody was detected in 39 of 94 PTR patients with a positive rate of 41.5%, and all of them were HLA-Ⅰ antibodies, and 1 case was accompanied by human platelet antigen (HPA) antibody. A total of 134 times of compatible platelets were supplied to 39 patients with HLA-Ⅰ antibody positive by using antibody avoidance matching method. And the total effective rate of transfusion was 97.8% (131/134); The PCI compliance rates of HLA-A antigen mismatch, HLA-B antigen mismatch and HLA-A and B antigen mismatch groups were 81.6% (31/38), 86.5% (32/37) and 78.6% (22/28), respectively. The total effective rate of transfusion was 97.4% (37/38), 94.6% (35/37) and 100% (28/28), respectively, with no statistical significance (all P>0.05). A total of 118 times of compatible platelets were provided by HLA antigen cross-reaction group genotype matching and serological cross-matching, 90 transfusion effects were collected during follow-up, and the total effective rate was 76.7% (69/90). Conclusion: The combination of different platelet matching schemes can improve the PCI compliance rate and the total effective rate of transfusion in PTR patients.

Pathogenetic analysis of transfusion-related acute lung injury caused by human leukocytes antigen antibody against human leukocyte antigen

From September 2019 to October 2020, pathogenetic analysis of three patients clinically diagnosed as transfusion-related acute lung injury (TRALI) caused by human leukocyte antibodies was conducted by Guangzhou Blood Centre, including 2 males and 1 female, aged 56, 50 and 20 years old, respectively. Solid phase agglutination, anti-human globulin test and flow cytometry method were used to detect the presence of antibodies against patients. Sequencing-based human leukocyte antigen (HLA-SBT) typing technique was used to detect the human leukocyte antigen (HLA) genotypes of patients. Lifecodes single antigen class Ⅰ/Ⅱ kit (LSA-Ⅰ/Ⅱ) were used to detect the specificity of HLA-class Ⅰ and class Ⅱ antibodies in donor blood by Luminex 200 liquid suspension chip system. The HLA specific antibodies and corresponding epitopes in donors were also analyzed. The results showed that HLA class Ⅰ or class Ⅱ specific antibodies against TRALI patients were detected in the blood donors. The plasma of donor 3 received by patient 1 contained antibodies against the patient's HLA-DRB1*09∶01 antigen, and the epitopes mediating the antibody reaction of the donor and recipient were 70R, 31I, 70QA. There were antibodies against the HLA-A*11∶02, HLA-A*11∶01, DRB1*12∶02, and DRB1*09∶01 antigens of patient 2 in the plasma of donor 4, and the associated antigenic epitopes were 151AHA, 57V, and 16Y. Antibodies against the HLA-DRB1*14∶04, DRB1*11∶01, and DPB1*05∶01 antigens of patient 3 were present in the plasma of donor 6 and donor 7, and the associated epitopes were 96HK, 140TV, 13SE, and 111K. Three cases of TRALI were confirmed to be caused by HLA antibodies through laboratory analysis, and human leukocyte antibody detection should be paid attention in clinically suspected cases of TRALI, and targeted diagnosis and treatment should be given.