Specific Ab Research Articles

Clinical characteristics and short-term outcomes of autoimmune encephalitis in adults

To characterize clinical, paraclinical features and short-term outcomes in different types of autoimmune encephalitis (AE) in a one-center cohort of Russian patients, as well as to evaluate the frequency and significance of the joint expression of antineuronal and anti-glial antibodies (Abs) in AE. Forty-one patients were diagnosed with AE at the Research Center of Neurology from November 2020 to December 2022. Demographic, clinical characteristics, results of laboratory tests, MRI of brain, treatment and outcomes of disease were analyzed. The analysis of Abs to glial antigens (myelin-oligodendrocyte glycoprotein - MOG, glial fibrillar acidic protein - GFAP, aquaporin 4 - AQP-4) was performed by indirect immunofluorescence assay (Euroimmun, Germany). In 24 (58.5%) patients was established definite AE, confirmed by specific Abs detection; in 2 (4.9%) - definite limbic encephalitis, in 15 (36.6%) - seronegative probable AE (including 3 cases of Hashimoto's encephalitis). GFAP-Abs in cerebrospinal fluid (CSF) were detected only in two patients - with clinical and MRI-picture of autoimmune GFAP-astrocytopathy (A-GFAP-A). GFAP- and MOG-Abs in the blood were detected in 25.7% and 6%, respectively, AQP-4-Abs were not detected. There were no correlations between co-expression with glial Abs and clinical characteristics. Systemic and antithyroid Abs were present in 15% and 31%, respectively. Paraneoplastic AE accounted for 22%. For the first time in the Russian population, 2 cases of A-GFAP-A, 6 cases of AE associated with COVID-19 were described. The most common first syndrome were epileptic seizure (34%), psychiatric (29%) and cognitive (14%) disorders. Relapses of AE was observed in 22%. Inflammatory changes in CSF were detected in 41%, focal changes on MRI in 68%. First-line immune therapy was performed in all patients, 85% of cases received pulse therapy with methylprednisolone. Second-line immune therapy (rituximab or cyclophosphamide intravenously) was performed in 19.5%, 78% of patients achieved significant improvement during treatment (scores ≤2 on the modified Rankin scale). The results allow us to consider COVID-19 as a trigger of AE. The absence of detection of GFAP-Abs in CSF in patients with other types of AE contributes to the confirmation of the specificity of GFAP-seropositivity of CSF for the diagnosis of A-GFAP-A. The expression of GFAP- and MOG-Abs in AE can serve as confirmation of the immuno-mediated etiology of the disease, which is especially important for the AE diagnosis in the absence of antineuronal Abs.

2125. Determinants of Placental Transfer of HSV-specific Antibodies and the Impact of SARS-CoV-2 Coinfection

Abstract Background Primary versus recurrent herpes simplex virus 1 or 2 (HSV-1 or HSV-2) infection during pregnancy carries a higher risk of neonatal herpes. Murine and clinical studies demonstrate that antibody dependent cellular cytotoxicity (ADCC) provides greater protection against disseminated neonatal disease. To quantify relative transfer of HSV specific Abs with different functions and targets and whether SARS-CoV-2 coinfection modified transfer, we conducted a prospective cohort study of mother-infant dyads prior to and during COVID-19. Methods Total and HSV lysate, glycoprotein D (gD) and glycoprotein B (gB)-specific IgG, IgG1 and IgG3, nAbs and ADCC were quantified in paired 3rd trimester maternal and cord blood. IgG1 and IgG3 subclass and gD or gB-specific Abs were isolated by column purification and glycan profiles were assessed using mass spectrometry. The pre-COVID study population included 21 term and 15 preterm dyads who were HSV seropositive and the pri-COVID cohort included 25 HSV seropositive term dyads whose mothers were also SARS-CoV-2 PCR and COVID Ab positive at delivery. Results HSV-specific Ab and neutralizing Ab transfer ratio (TR) were higher in term compared to preterm pre-COVID dyads (all p< 0.05), but the ADCC TR was < 1.0 for both groups. To determine if the low ADCC TR reflected antigenic target, subclass and/or glycans, we enriched for anti-gD and anti-gB specific and IgG1 and IgG3 Abs. The anti-gD Abs were exclusively IgG, had only neutralizing activity and had glycans associated with FcRn binding. In contrast, anti-gB Abs were both IgG1 and IgG3; had both neutralizing and ADCC activity and expressed glycans associated with both FcRn and FcγRIIIa binding. There was no significant difference in HSV-specific IgG TR in pre-COVID vs COVID dyads (0.42) but the nAb TR was lower (p=0.018) and ADCC TR higher (p< 0.001) in COVID compared to pre-COVID patients. Placental immunohistochemistry showed an increased colocalization of FcRn and FcγRIIIA in SARS-CoV-2 positive mothers, which would favor transfer of ADCC Abs. Conclusion Defining the determinants of ADCC transfer has implications for future vaccine and monoclonal Ab strategies to prevent/treat neonatal herpes. We speculate that increasing the transfer of ADCC may be a key element in providing immune protection Disclosures Betsy Herold, MD, Viracor (Eurofins): Advisor/Consultant|X-Vax, Technologies: Advisor/Consultant|X-Vax, Technologies: Grant/Research Support|X-Vax, Technologies: Serve on Scientific Advisory Board for X-Vax, Technologies and receiving reserach funding for related worl. Betsy Herold, MD, Viracor (Eurofins): Advisor/Consultant|X-Vax, Technologies: Advisor/Consultant|X-Vax, Technologies: Grant/Research Support|X-Vax, Technologies: Serve on Scientific Advisory Board for X-Vax, Technologies and receiving reserach funding for related worl.

Cellular assays to evaluate B-cell function

Inborn errors of immunity (IEI) that present with recurrent infections are largely due to antibody (Ab) deficiencies. Therefore, assessment of the B-cell and Ab compartment is a major part of immunologic evaluation. Here we provide an overview about cellular assays used to study B-cell function and focus on lymphocyte proliferation assay (LPA), opsonophagocytic assay (OPA), and the Enzyme-linked Immunosorbent Spot Assay (ELISPOT) including clinical applications and limitations of these techniques. LPAs assess ex-vivo cell proliferation in response to various stimuli. Clinically available LPAs utilize peripheral blood mononuclear cells and mostly assess T-cell proliferation with pokeweed mitogen considered the most B-cell specific stimulus. In the research setting, isolating B cells or using more B-cell specific stimuli such as CD40L with IL-4/IL-21 or the TLR9 ligand CpG can more specifically capture the proliferative ability of B cells. OPAs are functional in-vitro killing assays used to evaluate the ability of IgG Ab to induce phagocytosis applied when assessing the potency of vaccine candidates or along with avidity assays to evaluate the quality of secreted IgG. The B-cell ELISPOT assesses Ab production at a cellular level and can characterize the Ab response of particular B-cell subtypes. It can be used in patients on IgG therapy by capturing specific Abs produced by individual B cells, which is not affected by exogenous IgG from plasma donors, and when assessing the vaccine response in patients on immunomodulatory drugs that can affect memory B-cell function. Emerging approaches that are only available in research settings are also briefly introduced.

Interim Results of a Prospective Trial Testing Vaccination Against Pneumococcus before and after CD19 CAR T Cell Therapy to Optimize Humoral Immunity

Background CD19 targeted CAR T cell therapy (CAR-T) can lead to B cell aplasia, and CAR-T patients often have few protective antibodies (Abs) against polysaccharide antigens such as Streptococcus pneumoniae (Walti et al, JCI Insight, 2021). We previously reported that vaccinating CAR-T patients with PCV13, pneumococcal 13-valent conjugate vaccine, did not induce humoral protection when given at 3- or 6-months post therapy (Lee et al, EBMT, 2021). Subsequently, some patients developed humoral protection following vaccination at day+360 or maintained seroprotective IgG Abs present at baseline. Here we present interim results of a Simons two-stage design phase II trial (NCT04745559) testing the hypothesis that PCV13 given before and after CAR-T will induce humoral protection against pneumococcus among CAR-T patients. Method Eligible patients were ≥18 years old with large B cell lymphoma (LBCL) and under consideration for CAR-T. All patients received PCV13 7 days (range, 4-21) before apheresis and again at day+30 (range, 21-37) and day+90 (range, 75-115) post infusion. Pre- and post-serum pneumococcal IgG Abs were drawn to assess humoral response. Pneumococcal serotypes tested include those specific (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F) and non-specific (8, 9N, 12F) to PCV13 vaccine. An established serotype specific IgG concentration ≥1.3µg/mL was considered protective, and a patient with ≥6/11 tested vaccine specific serotypes meeting this threshold was deemed to have long-term humoral protection against pneumococcus. Descriptive analysis was conducted for patient characteristics and paired nonparametric t-test was performed to compare absolute IgG Abs between pre-and post-vaccination timepoints. Results As of 7/01/2022, 7 enrolled patients were evaluable for immune response to vaccine. Median age was 65 (range, 43-75). Four patients received prior autologous stem cell transplant and had history of PCV vaccination. At baseline, only 1 out of 7 patients met the criteria of humoral protection. Three patients had CD19+ B cell count ≤5 cells/ul, and 1 patient had IgG level <400mg/dl. Seven patients received the first PCV13 before apheresis. Out of 6 patients, who did not have humoral protection at baseline, 2 patients achieved humoral protection prior to the start of conditioning chemotherapy. The patient with humoral protection at baseline had vaccine specific IgG Abs remain similar between these timepoints (P=0.99). One patient withdrew from the study before day+30, after developing ICANS grade 3. Six patients proceeded to receive the second dose of PCV13, 5 with paired Abs at day+30 and day+90. Two patients who achieved humoral protection with the first vaccine maintained humoral protection at day+30, and one of them subsequently lost protection at day+90. Three patients who did not have humoral protection since baseline did not mount humoral protection at day+90, after the second vaccine was administered at day+30. Before day+90, 1 patient contracted COVID infection and did not receive the third vaccine. Five patients proceeded to receive the third PCV13 at day+90, and of these patients, 3 patients had paired Abs at day+90 and day+180. One patient who achieved humoral protection with the first vaccine and lost the immunity at day+90 successfully achieved humoral protection again with the third vaccine (Figure 1). Patients’ clinical characteristics and laboratory values are presented in Table 1. As compared to other subjects, Subject 001 who responded to the first and third vaccine had CD19+ B cells prior to CAR-T and recovery of CD19+ B cells at day+180. There were no adverse events related to PCV13. Conclusion Interim results from this prospective clinical trial demonstrate that few LBCL patients had humoral protection against pneumococcus at baseline. Some patients responded to PCV13 given prior to CAR-T, and the immunity was maintained post CAR-T. PCV13 did not induce humoral protection when given at day+30, but one patient who responded to the first vaccine successfully achieved humoral protection again with the vaccine given at day+90. This patient's characteristics were notable for CD19+ B cells present prior to CAR-T and recovered at day+180. PCV13 vaccine was well tolerated in all patients enrolled in this trial. Additional biomarker analysis is ongoing including evaluation for cellular immune response against the vaccine adjuvant. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Development of a High-Affinity Antibody against the Tumor-Specific and Hyperactive 611-p95HER2 Isoform.

Simple SummaryIn the present study, we addressed the unmet need for a molecular antibody (mAb) with high affinity and specificity against a truncated hyperactive isoform of human epidermal growth factor receptor 2 (HER2), called 611-carboxy terminal fragment (CTF)-p95HER2. Patients with p95HER2+ breast cancer are at risk of developing metastatic breast cancer with a poor prognosis and resistance to therapies targeting full-length HER2. We have generated a mAb named Oslo-2, which react specifically with 611-CTF-p95HER2 and has a high affinity. We also characterized the antigenic determinant (epitope) on the p95HER2 protein and the antigen-binding site (paratope) on the Oslo-2 mAb. The antibody can be used to develop antibody- or cell-based therapies targeting p95HER2, as well as a diagnostic assay to identify p95HER2+ disease.The expression of human epidermal growth factor receptor 2 (HER2) is a key classification factor in breast cancer. Many breast cancers express isoforms of HER2 with truncated carboxy-terminal fragments (CTF), collectively known as p95HER2. A common p95HER2 isoform, 611-CTF, is a biomarker for aggressive disease and confers resistance to therapy. Contrary to full-length HER2, 611-p95HER2 has negligible normal tissue expression. There is currently no approved diagnostic assay to identify this subgroup and no therapy targeting this mechanism of tumor escape. The purpose of this study was to develop a monoclonal antibody (mAb) against 611-CTF-p95HER2. Hybridomas were generated from rats immunized with cells expressing 611-CTF. A hybridoma producing a highly specific Ab was identified and cloned further as a mAb. This mAb, called Oslo-2, gave strong staining for 611-CTF and no binding to full-length HER2, as assessed in cell lines and tissues by flow cytometry, immunohistochemistry and immunofluorescence. No cross-reactivity against HER2 negative controls was detected. Surface plasmon resonance analysis demonstrated a high binding affinity (equilibrium dissociation constant 2 nM). The target epitope was identified at the N-terminal end, using experimental alanine scanning. Further, the mAb paratope was identified and characterized with hydrogen-deuterium-exchange, and a molecular model for the (Oslo-2 mAb:611-CTF-p95HER2) complex was generated by an experimental-information-driven docking approach. We conclude that the Oslo-2 mAb has a high affinity and is highly specific for 611-CTF-p95HER2. The Ab may be used to develop potent and safe therapies, overcoming p95HER2-mediated tumor escape, as well as for developing diagnostic assays.

The Immunocytokine FAP-IL-2v Enhances Anti-Neuroblastoma Efficacy of the Anti-GD2 Antibody Dinutuximab Beta.

Simple SummarySince IL-2 co-treatment did not show any therapeutic benefit in the GD2-directed treatment of high-risk neuroblastoma (NB) but strongly induced regulatory T cells (Treg), we investigated here the immunocytokine FAP-IL-2v stimulating NK and cytotoxic T cells without induction of Treg. We first detected FAP on NB- and myeloid-derived suppressor cells (MDCS) in tumor tissue and showed a tumor-cell-dependent enhancement in FAP expression by fibroblasts. Treatment of leukocytes with FAP-IL-2v increased ADCC mediated by the anti-GD2 antibody dinutuximab beta (DB) against NB cells. We next evaluated the antitumor efficacy of a combinatorial immunotherapy by applying DB and FAP-IL-2v and observed strongly reduced tumor growth and improved survival in experimental mice. Analysis of tumor tissue revealed increased NK and cytotoxic T cell numbers and reduced Treg compared to controls. Our data show that FAP-IL-2v is a potent immunocytokine that augments the efficacy of DB against NB, providing a promising alternative to IL-2.Treatment of high-risk neuroblastoma (NB) patients with the anti-GD2 antibody (Ab) dinutuximab beta (DB) improves survival by 15%. Ab-dependent cellular cytotoxicity (ADCC) is the major mechanism of action and is primarily mediated by NK cells. Since IL-2 co-treatment did not show a therapeutic benefit but strongly induced Treg, we investigated here a DB-based immunotherapy combined with the immunocytokine FAP-IL-2v, which comprises a fibroblast activation protein α (FAP)-specific Ab linked to a mutated IL-2 variant (IL-2v) with abolished binding to the high-affinity IL-2 receptor, thus stimulating NK cells without induction of Treg. Effects of FAP-IL-2v on NK cells, Treg and ADCC mediated by DB, as well as FAP expression in NB, were investigated by flow cytometry, calcein-AM-based cytotoxicity assay and RT-PCR analysis. Moreover, the impact of soluble factors released from tumor cells on FAP expression by primary fibroblasts was assessed. Finally, a combined immunotherapy with DB and FAP-IL-2v was evaluated using a resistant syngeneic murine NB model. Incubation of leukocytes with FAP-IL-2v enhanced DB-specific ADCC without induction of Treg. FAP expression on NB cells and myeloid-derived suppressor cells (MDCS) in tumor tissue was identified. A tumor-cell-dependent enhancement in FAP expression by primary fibroblasts was demonstrated. Combination with DB and FAP-IL-2v resulted in reduced tumor growth and improved survival. Analysis of tumor tissue revealed increased NK and cytotoxic T cell numbers and reduced Treg compared to controls. Our data show that FAP-IL-2v is a potent immunocytokine that augments the efficacy of DB against NB, providing a promising alternative to IL-2.

Active immunotherapy against pathogenic Cis pT231-tau suppresses neurodegeneration in traumatic brain injury mouse models

Traumatic brain injury (TBI), characterized by acute neurological impairment, is associated with a higher incidence of neurodegenerative diseases, particularly chronic traumatic encephalopathy (CTE), Alzheimer's disease (AD), and Parkinson's disease (PD), whose hallmarks include hyperphosphorylated tau protein. Recently, phosphorylated tau at Thr231 has been shown to exist in two distinct cis and trans conformations. Moreover, targeted elimination of cis P-tau by passive immunotherapy with an appropriate mAb that efficiently suppresses tau-mediated neurodegeneration in severe TBI mouse models has proven to be a useful tool to characterize the neurotoxic role of cis P-tau as an early driver of the tauopathy process after TBI. Here, we investigated whether active immunotherapy can develop sufficient neutralizing antibodies to specifically target and eliminate cis P-tau in the brain of TBI mouse models. First, we explored the therapeutic efficacy of two different vaccines. C57BL/6 J mice were immunized with either cis or trans P-tau conformational peptides plus adjuvant. After rmTBI in mice, we found that cis peptide administration developed a specific Ab that precisely targeted and neutralized cis P-tau, inhibited the development of neuropathology and brain dysfunction, and restored various structural and functional sequelae associated with TBI in chronic phases. In contrast, trans P-tau peptide application not only lacked neuroprotective properties, but also contributed to a number of neuropathological features, including progressive TBI-induced neuroinflammation, widespread tau-mediated neurodegeneration, worsening functional deficits, and brain atrophy. Taken together, our results suggest that active immunotherapy strategies against pathogenic cis P-tau can halt the process of tauopathy and would have profound clinical implications.

Sars-Cov-2 Specific Antibody Detection in Health Care Workers in Tertiary Care Hospital

Objective: To estimate the sero-positivity of SARS-CoV-2 in health care workers based on specific antibodies in a tertiary care hospital.&#x0D; Study Design: Comparative cross-sectional study.&#x0D; Place and Duration of Study: Combined Military Hospital Kohat Pakistan, Jun to Jul 2020.&#x0D; Methodology: 292 Health Care Workers from different departments were included by non-probability consecutive sampling. They were divided into three groups (High risk, Intermediate risk and low risk) according to the exposure risk to COVID-19 patients. In addition, serum samples for SARS- CoV-2 specific quantitative antibodies were collected. The odds ratio for SARSCoV-2 Ab risk was calculated for different risk groups and male and female health care workers.&#x0D; Result: Out of 292 Health Care Workers, 243 (83.22%) were male, and 49 (16.78%) were female, with a mean age of 34.64 ± 7.25 years. SARS- CoV-2 specific Ab was detected in 43 (14.72%) individuals. The risk of sero-positivity was higher in the high-risk group than the intermediate-risk group (Odds ratio 1.171 vs 0.878) and higher in the intermediate-risk group than the low-risk group (odds ratio 1.120 vs 0.747). The risk was also higher in females than in males (Odds ratio 1.676 vs 0.878).&#x0D; Conclusion: The sero-positivity of SARS-CoV-2 in healthcare workers in tertiary care hospitals is high. The results indicate that we must improve our local hygiene and protective standards.

Efficacy of prepartum vaccination against neonatal calf diarrhea in Nelore dams as a prevention measure

BackgroundNeonatal calf diarrhea (NCD) is the leading cause of calf morbidity and mortality in beef cattle. Cow’s vaccination in last stage of pregnancy is one of the most important measures to mitigate the risk of NCD outbreaks. The aim of this study was to evaluate the efficacy of prepartum single dose vaccination against NCD, especially Bovine Rotavirus type A (BoRVA) and Bovine Coronavirus (BCoV), in Nelore dams and offspring. A total of 117 pregnant cows (n = 81) and heifers (n = 36) were distributed in two groups, vaccinated (VAC: cows = 40; heifers = 19) and non-vaccinated (NVAC: cows = 41; heifers = 17). Vaccination occurred between 60 to 50 days before the expected calving date with a single dose of a water-in-oil (W/O) vaccine, and NVAC group received a dose of saline solution 0.9%. Blood samples were collected before vaccination and 30 days after to evaluate the antibody (Ab) response. Specific IgG1 Abs against BoRVA and BCoV were measured by using an Enzyme Linked Immuno Sorbent Assay (ELISA). Calves’ births were monitored, and the transference of passive immunity was evaluated. Diarrhea was monitored in the first 30 days of age, and fecal samples were collected for identification of the etiological agent.ResultsHigher titers of IgG1 Ab against BoRVA and BCoV was observed in the VAC group than NVAC group in the cow (P < 0.0001) and total dams categories (P < 0.0001). The titer of specific IgG1 Abs in the calves’ serum reflected the dams response, observing higher IgG1 Ab titers for BoRVA (P < 0.0016) and BCoV (P < 0.0095) in the offspring born to VAC cows and higher IgG1 Ab titers for BoRVA(P < 0.0171) and BCoV (P < 0.0200) in the offspring born to VAC total dams. The general incidence of diarrhea observed was 18.6% (11/59) and 29.3% (17/58) in the calves born to the VAC and NVAC group, respectively.ConclusionsPrepartum vaccination with a single dose of the vaccine tested increased the titers of IgG1 Ab against BCoV and BoRVA, and it could be used as a preventive strategy to decrease the NCD occurrence in Nelore calves.

Antibody Response to SARS-CoV-2 Infection in Non Vaccinated Health Care Personnel

Background: Antibodies (Abs) are produced by B cells after infection with the SARS/COVID-19 virus. The presence of neutralizing antibody is an indicator of protective immunity for most viral infections. But, we still don’t know how long and how effectively this immune protection will cover. Objectives: This study aimed to estimate the antibodies level in PCR-confirmed COVID-19 subjects in non vaccinated healthcare personnel. Methods: SARS-CoV-2 specific total Abs (IgG and IgM), IgG of nucleocapsid (N) protein and spike (S) protein levels were estimated using two clinically validated and widely used serological assays, detecting antibodies against the Total Antibody, nucleocapsid(N) and spike(S) proteins. Results: A total 130 subjects with PCR-confirmed SARSCoV- 2 infection were included in this study and all subjects were symptomatic and blood samples were collected between 3 to 24 weeks. Of all participants, about 52% were female and mean age was 43.2 years. The study found that the Total Abs, IgG of N protein and neutralizing Abs of S protein were developed 100%, 74.6% and 93.8% respectively. The study also found that the IgG titers of the N protein peaked at about 19 weeks after onset and decreased thereafter. The study also found that the neutralizing Abs of S protein were gradually increasing in the second phase of (9wks-19wks) weeks and in the third phase of (19wks -24wks) weeks after disease onset than compared to the first phase of weeks (3wks- 9wks) and it was significant (p&lt;0.001). Conclusion: The study concluded that the antibodies, total Abs, IgG titer of N protein and neutralizing Abs of S protein were developed 100%, 74.6% and 93.8% respectively. The study also observed that IgG of N protein was decreasing within 19-24 weeks and neutralizing Abs of S protein peaked at 19-24 weeks after the onset of disease. J Bangladesh Coll Phys Surg 2022; 40: 191-196

Comparative Profiles of SARS-CoV-2 Spike-Specific Human Milk Antibodies Elicited by mRNA- and Adenovirus-Based COVID-19 Vaccines.

Background: Numerous COVID-19 vaccines are authorized globally. To date, ∼71% of doses comprise the Pfizer/BioNTech vaccine, and ∼17% the Moderna/NIH vaccine, both of which are messenger RNA (mRNA) based. The chimpanzee Ad-based Oxford/AstraZeneca (AZ) vaccine comprises ∼9%, while the Johnson & Johnson/Janssen (J&J) human adenovirus (Ad26) vaccine ranks fourth at ∼2%. No COVID-19 vaccine is yet available for children 0-4. One method to protect this population may be passive immunization through antibodies (Abs) provided in the milk of a lactating vaccinated person. Our early work and other reports have demonstrated that unlike the post-SARS-CoV-2 infection milk Ab profile, which is rich in specific secretory (s)IgA, the vaccine response is highly IgG dominant. Results: In this report, we present a comparative assessment of the milk Ab response elicited by Pfizer, Moderna, J&J, and AZ vaccines. This analysis revealed 86-100% of mRNA vaccine recipient milk exhibited Spike-specific IgG endpoint titers, which were 12- to 28-fold higher than those measured for Ad vaccine recipient milk. Ad-based vaccines elicited Spike-specific milk IgG in only 33-38% of recipients. Specific IgA was measured in 52-71% of mRNA vaccine recipient milk and 17-23% of Ad vaccine recipient milk. J&J recipient milk exhibited significantly lower IgA than Moderna recipients, and AZ recipients exhibited significantly lower IgA titers than Moderna and Pfizer. Less than 50% of milk of any group exhibited specific secretory Ab, with Moderna recipient IgA titers measuring significantly higher than AZ. Moderna appeared to most frequently elicit greater than twofold increases in specific secretory Ab titer relative to prevaccine sample. Conclusion: These data indicate that current Ad-based COVID-19 vaccines poorly elicit Spike-specific Ab in milk compared to mRNA-based vaccines, and that mRNA vaccines are preferred for immunizing the lactating population. This study highlights the need to design vaccines better aimed at eliciting an optimal milk Ab response.

Phase 1a/1b study of FOR46, an antibody drug conjugate (ADC), targeting CD46 in metastatic castration-resistant prostate cancer (mCRPC).

3001 Background: FOR46, a fully human antibody (ab) conjugated to monomethyl auristatin E (MMAE), targets a tumor selective epitope of CD46, which is highly expressed in mCRPC and treatment-emergent small cell neuroendocrine cancer (t-SCNC). CD46 is enriched in tumor cells upon treatment with androgen signaling inhibitors (ASI). Following dose escalation (Phase 1a), dose expansion was undertaken in 2 cohorts (Phase 1b): 1) Pts with de novo or t-SCNC and 2) pts with mCRPC without a t-SCNC component. Pts with adenocarcinoma enrolled in dose escalation and expansion are included in this analysis. Methods: Eligible pts had mCRPC, with progression on at least 1 ASI, with no prior chemotherapy for CRPC. Phase 1a pts received FOR46 0.1-3.0 mg/kg IV Q3 weeks (wks). The primary objectives in phase 1a were to assess adverse effects (AEs) and select the phase 1b dose; and in phase 1b to assess efficacy. For phase 1b, tumor biopsy in the CRPC setting for assignment to the 2 cohorts was required. CD46 expression was not required for inclusion in the expansion cohort, but was evaluated using a non-epitope specific CD46 polyclonal ab. Histology and CD46 expression were centrally reviewed. Results: Thirty-three pts were enrolled in phase 1a and 10 in phase 1b (including 6 treated in ph1a at the expansion dose or higher). Overall, 36 pts were treated at doses &gt; 1.2 mg/kg. Following excess toxicity in pts with body mass indices &gt; 30 (3 of 3 with Gr 4 neutropenia and 1 of 3 with Gr 3 fatigue at 2.4 mg/kg), further dosing was calculated using adjusted body weight (AJBW) rather than actual weight, allowing escalation to 3.0 mg/kg. The 2.7 mg/kg dose by AJBW was determined to be the MTD and phase 1b dose. The most common AEs at the 2.7 mg/kg dose were neutropenia (77% Gr 3 or 4), infusion reactions (37%, all &lt; Gr 2), fatigue (31%, all &lt; Gr 2) and peripheral neuropathy (24%, all &lt; Gr 2)). Fourteen of 31 evaluable pts (45.2%) at &gt; 1.2 mg/kg achieved a PSA50 response with 10 (32.3%) confirmed. Five pts were not evaluable for PSA response; 3 had no post-baseline PSA and 2 had baseline PSA &lt; 1 ng/mL. The median duration of confirmed PSA50 response is &gt;16 wks (range 6-48+ wks, with 4 ongoing at 12, 24, 25 and 48 wks). 18 pts had measurable lesions; 8 of 18 (44.4%) had tumor regression, with 4 (22.2%) confirmed partial responses (PR). The median duration of response is &gt; 14 wks (range 9 -31+ weeks with 2 ongoing at 13 and 31 wks). Eight pts were evaluable for CD46 expression with a median H-score of 245 (range 0-300). Two pts with PRs had H-scores of 15 and 300; 4 with confirmed PSA50 had H-scores of 10, 15, 40 and 300. Conclusions: FOR46, a novel ADC targeting CD46, demonstrates clinical activity in mCRPC pts, with an acceptable safety profile, similar to other MMAE-containing ADCs. FOR46 merits further investigation in pts with mCRPC, alone and in combination with agents that enhance CD46 expression. Clinical trial information: NCT03575819.

Hem-1 regulates protective humoral immunity and limits autoantibody production in a B cell-specific manner.

Hematopoietic protein-1 (Hem-1) is a member of the actin-regulatory WASp family verprolin homolog (WAVE) complex. Loss-of-function variants in the NCKAP1L gene encoding Hem-1 were recently discovered to result in primary immunodeficiency disease (PID) in children, characterized by poor specific Ab responses, increased autoantibodies, and high mortality. However, the mechanisms of how Hem-1 deficiency results in PID are unclear. In this study, we utilized constitutive and B cell–specific Nckap1l-KO mice to dissect the importance of Hem-1 in B cell development and functions. B cell–specific disruption of Hem-1 resulted in reduced numbers of recirculating follicular (FO), marginal zone (MZ), and B1 B cells. B cell migration in response to CXCL12 and -13 were reduced. T-independent Ab responses were nearly abolished, resulting in failed protective immunity to Streptococcus pneumoniae challenge. In contrast, T-dependent IgM and IgG2c, memory B cell, and plasma cell responses were more robust relative to WT control mice. B cell–specific Hem-1–deficient mice had increased autoantibodies against multiple autoantigens, and this correlated with hyperresponsive BCR signaling and increased representation of CD11c+T-bet+ age-associated B cell (ABC cells) — alterations associated with autoimmune diseases. These results suggest that dysfunctional B cells may be part of a mechanism explaining why loss-of-function Hem-1 variants result in recurring infections and autoimmunity.

A Longitudinal Study of Humoral Immune Responses to SARS-CoV-2 Spike Proteins in Gamma-Interferon-inducible Lysosomal Thiol Reductase Deficient Mice

Abstract The disulfide (S-S) bonds located in the receptor binding domain (RBD) of Spike (S) proteins of SARS-CoV-2 are critical for structural folding and viral entry. Once entered cells, S proteins, like other exogenous Ag, can be transported into endo/lysosomes, where gamma-interferon-inducible lysosomal thiol reductase (GILT) is the only thiol reductase located, which can reduce S-S bonds. GILT mediated S-S bond reduction in APC is critical in unfolding of native S-S bonds containing Ag, subsequently processing/presenting Ag, and, finally, triggering CD4 T cell responses. Recently, we also find GILT plays a role in Ab responses. Whether GILT mediates anti-SARSCoV-2 host defense responses remains unknown. We hypothesized that GILT is important in eliciting host humoral immune responses against SARS-CoV-2 by reducing S-S bonds and exposing Ag epitopes. To address this, we used 3 different types of S protein derived Ag to immunize GILT KO or B6 control mice and measured the specific Ab responses in a longitudinal study. GILT KO or B6 wildtype mice were given RBD, S1 region and the full length of extracellular domain of S proteins with CFA initially, and boosted at week 3 with the same Ag in IFA. Sera were collected at weeks 3 and 5, months 3, 4 and 5 for quantification of specific anti-RBD, S1 and S Ab. At all timepoints examined, GILT KO mice generated lower specific Ab titers to the immunogens, as compared to B6. Furthermore, decay of anti-specific Ab in GILT KO was faster than that in controls after immunization. Our preliminary findings showed an important role of GILT in humoral immune responses against SARS-CoV-2, suggesting unfolding S-S bonds is critical in this process. Recombinant GILT as a therapeutic might benefit patients with COVID-19. Supported by Seed Grant, Univ. of Utah

Pharmacologically Inferred Glycolysis and Glutaminolysis Requirement of B Cells in Lupus-Prone Mice.

Several studies have shown an enhanced metabolism in the CD4+ T cells of lupus patients and lupus-prone mice. Little is known about the metabolism of B cells in lupus. In this study, we compared the metabolism of B cells between lupus-prone B6.Sle1.Sle2.Sle3 triple-congenic mice and C57BL/6 controls at steady state relative to autoantibody production, as well as during T cell-dependent (TD) and T cell-independent (TI) immunizations. Starting before the onset of autoimmunity, B cells from triple-congenic mice showed an elevated glycolysis and mitochondrial respiration, which were normalized in vivo by inhibiting glycolysis with a 2-deoxy-d-glucose (2DG) treatment. 2DG greatly reduced the production of TI-Ag-specific Abs, but showed minimal effect with TD-Ags. In contrast, the inhibition of glutaminolysis with 6-diazo-5-oxo-l-norleucine had a greater effect on TD than TI-Ag-specific Abs in both strains. Analysis of the TI and TD responses in purified B cells in vitro suggests, however, that the glutaminolysis requirement is not B cell-intrinsic. Thus, B cells have a greater requirement for glycolysis in TI than TD responses, as inferred from pharmacological interventions. B cells from lupus-prone and control mice have different intrinsic metabolic requirements or different responses toward 2DG and 6-diazo-5-oxo-l-norleucine, which mirrors our previous results obtained with follicular Th cells. Overall, these results predict that targeting glucose metabolism may provide an effective therapeutic approach for systemic autoimmunity by eliminating both autoreactive follicular Th and B cells, although it may also impair TI responses.

Severe acute respiratory syndrome coronavirus 2 vaccination induces short-term polyclonal antibody response against seasonal endemic coronaviruses

Abstract Antibody (Ab) responses induced by endemic human coronaviruses (HCoVs) may affect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific Ab production due to cross-reactivity among these HCoVs. To explore this hypothesis, we collected serum samples of healthy healthcare workers (HCW) at four time-points: pre-vaccination, post-vaccination (1st and 2nd dose) and 6 months post-vaccination. We used N protein peptide-based enzyme-linked immunosorbent assays (ELISA) specific for alphaCoVs (NL63 and 229E) and betaCoVs (OC43 and HKU1) as well as N and S peptide-based ELISA for SARS-CoV-2. Low levels of SARS-CoV-2 N protein-specific Abs were present in some individuals prior to vaccination. The level remained constant following one or two doses of vaccine and declined after 6 months. SARS-CoV-2 S protein-specific Abs level were low in most individuals prior to vaccination, increased sharply following 1st and 2nd vaccinations and declined by 6 months. We observed low levels of pre-existing IgG Abs against endemic HCoVs prior to COVID-19 vaccination. However, like SARS-CoV-2-specific IgG Ab titers, they increased (1.6–1.9-fold) following SARS-CoV-2 vaccination and waned 6 months later. IgG Abs surge targeting HCoV N protein suggest polyclonal activation of memory B cell responses induced by the S gene based COVID-19 vaccines. The levels of IgG Abs against endemic HCoVs were 1.1–1.5 times higher in SARS-CoV-2 seropositive vs. seronegative individuals, suggesting serological cross-reactivity between SARS-CoV-2 and other HCoVs. In summary, short-term immunity (six months) against common cold causing HCoVs can be reactivated following COVID-19 vaccination however it requires booster dose for long term protection.

Monoclonal antibodies from B cells of patients with anti-MDA5 antibody-positive dermatomyositis directly stimulate interferon gamma production

Anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab) positive dermatomyositis (anti-MDA5 DM) is a rare entity associated with poor prognosis and multiple immunologic abnormalities. These include the presence of autoAbs and deleterious interferon (IFN)-gamma production in the severe form of the disease. Here, we show that the autoAbs profile differs between patients, depending on disease severity, and that autoAbs from B cells of patients directly stimulate IFN-gamma production by peripheral blood cells. Serum of 29 anti-MDA5 DM patients were analyzed by indirect immunofluorescence (IIF) on Hep-2 cells, to identify patterns associated with poor outcome. Seventeen (59%) serum gave a specific cytoplasmic MDA5 pattern on Hep-2 cells, while 12 (41%) gave an unspecific pattern. Specific MDA5 pattern was associated with a higher risk to develop interstitial lung disease (p = 0.003). Monoclonal autoAbs were generated from B cell clones of two patients with extreme clinical presentation, one who developed a lethal form of the disease, and the other with a favorable outcome. Supernatants of the autoreactive B cell clones that gave an IIF cytoplasmic pattern were tested for their abilities to stimulate IFN-gamma production by peripheral blood cells. Out of 120,000 B cell clones analyzed, 12 produced monoclonal Abs that triggered direct IFN-gamma secretion by peripheral blood cells, by a monocyte-dependent mechanism. None of them was directed against the MDA5 antigen. Altogether, these findings demonstrated that autoAbs other than the highly specific anti-MDA5 Ab are direct contributors of the IFN-gamma upregulation that is linked to the severity of the disease.

Cutting Edge: Effect of Disease-Modifying Therapies on SARS-CoV-2 Vaccine-Induced Immune Responses in Multiple Sclerosis Patients.

Multiple sclerosis (MS) is a demyelinating inflammatory disease of the CNS treated by diverse disease-modifying therapies that suppress the immune system. Severe acute respiratory syndrome coronavirus 2 mRNA vaccines have been very effective in immunocompetent individuals, but whether MS patients treated with modifying therapies are afforded the same protection is not known. This study determined that dimethyl fumarate caused a momentary reduction in anti-Spike (S)-specific Abs and CD8 T cell response. MS patients treated with B cell-depleting (anti-CD20) or sphingosine 1-phosphate receptor agonist (fingolimod) therapies lack significant S-specific Ab response. Whereas S-specific CD4 and CD8 T cell responses were largely compromised by fingolimod treatment, T cell responses were robustly generated in anti-CD20-treated MS patients, but with a reduced proportion of CD4+CXCR5+ circulating follicular Th cells. These data provide novel information regarding vaccine immune response in patients with autoimmunity useful to help improve vaccine effectiveness in these populations.

210 Antibody function, antigenic target and glycans determine the transfer of herpes simplex virus (HSV) antibodies (Abs) from mothers to newborns and transfer is altered by SARS-CoV-2

OBJECTIVES/GOALS: Murine and clinical data suggest that antibody-dependent cellular cytotoxicity (ADCC) is associated with greater protection against disseminated neonatal HSV disease. To quantify the relative transfer of Abs with different functions and targets, we conducted a prospective study of mother-infant term and preterm dyads pre and during COVID-19 METHODS/STUDY POPULATION: Total and HSV lysate, glycoprotein D (gD) and glycoprotein B (gB)-specific IgG, IgG1 and IgG3 as well as HSV neutralizing Abs (nAbs) and ADCC were quantified in paired 3rd-trimester pregnant women and their newborns (cord) blood. Transfer ratios (TR) were defined as cord:maternal Ab levels. IgG1 and IgG3 subclass and gD or gB-specific Abs were isolated by column purification and glycan profiles were assessed by mass spectrometry. The study population included 21 term and 15 preterm dyads who were HSV-1 (+/- HSV-2) seropositive enrolled between 2018-2019 (pre-COVID) and 25 additional HSV-1 (+/- HSV-2) seropositive term dyads whose mothers were SARS-CoV-2 PCR and COVID Ab+ at delivery; 14 were asymptomatic and 11 had mild-moderate COVID disease. None of the mothers had active genital HSV lesions during delivery RESULTS/ANTICIPATED RESULTS: Anti-HSV IgG, IgG1 and IgG3 TR were higher in term vs. preterm dyads (p&lt;0.05). The nAb TR was 2.4 in term vs. 0.8 in preterm (p&lt;0.001) but the ADCC TR was &lt; 1.0 for both. To determine if the latter reflected antigenic target, subclass or glycans, we enriched for gD and gB specific and IgG1 and IgG3 Abs. The gD Abs were IgG1 and had only neutralizing activity. In contrast, gB Abs were polyfunctional and included IgG1 and IgG3 but only the IgG1 Abs had ADCC activity. The gD Abs were enriched for glycans associated with an affinity for the neonatal Fc receptor (FcRn); gB Abs expressed glycans associated with both FcRn and FcγRIIIa binding. There was no significant difference in total HSV-specific IgG TR in pre-COVID vs post-COVID dyads but the nAb TR was lower (p=0.018) and ADCC TR higher (p&lt;0.001) in the COVID compared to pre-COVID cohort DISCUSSION/SIGNIFICANCE: HSV ADCC Abs, which may provide greater protection than nAbs against neonatal disease, transfer poorly particularly to preterm newborns. However, in the setting of SARS-CoV-2, the TR of HSV ADCC is significantly higher. This may reflect alterations in the placental architecture and/or glycan composition which is currently being investigated.

Elevated CD21low B Cell Frequency Is a Marker of Poor Immunity to Pfizer-BioNTech BNT162b2 mRNA Vaccine Against SARS-CoV-2 in Patients with Common Variable Immunodeficiency

PurposeLimited data is available on the effect of COVID-19 vaccination in immunocompromised individuals. Here, we provide the results from vaccinating a single-center cohort of patients with common variable immunodeficiency (CVID).MethodsIn a prospective, open-label clinical trial, 50 patients with CVID and 90 age-matched healthy controls (HC) were analyzed for SARS-CoV-2 spike antibody (Ab) production after one or two doses of the Pfizer-BioNTech BNT162b2 mRNA vaccine. Additionally, in selected patients, SARS-CoV-2 spike-specific T-cells were assessed.ResultsA potent vaccine-induced anti-spike–specific IgG Ab response was observed in all the HC. In contrast, only 68.3% of the CVID patients seroconverted, with median titers of specific Ab being 83-fold lower than in HC. In fact, only 4/46 patients (8.6%) of patients who were seronegative at baseline reached the threshold for an optimal response (250 U/mL). Using the EUROclass definition, patients with either a reduced proportion, but not absolute counts, of switched memory B-cells or having an increased frequency of CD21low B-cells generally generated poor vaccine responses. Overall, CVID-patients had reduced spike-specific IFN-γ positive CD4+ T cell responses 2 weeks after the second dose, compared to HC. The total CD4 and CD4 central memory cell counts correlated with humoral immunity to the vaccine.ConclusionsCVID patients with low frequency of switched memory B-cells or an increased frequency of CD21low B-cells according to the EUROclass definition demonstrated poor responses to Pfizer-BioNTech BNT162b2 mRNA vaccination. Cellular immune responses were significantly affected, affirming that the defect in CVID is not limited to humoral immunity.