Magnitude Of Humoral Immune Response Research Articles

MO191: Humoral Immune Response of the Additional Chadox1 NCOV-19 Vaccine Following a Two-Dose Inactivated Whole-Virus SARS-COV-2 Vaccination in Patients on Dialysis

BACKGROUND AND AIMSPatients with end-stage kidney disease (ESKD) are at risk of coronavirus disease 2019 infection and its associated complications. A previous study demonstrated that patients with ESKD on dialysis generated suboptimal humoral immune response (HIR) and lower seroconversion rate after two-dose inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination as compared to healthy individuals. In this study, we examined HIR of the additional dose of ChAdOx1 nCoV-19 vaccine following a standard two-dose inactivated whole-virus SARS-CoV-2 vaccination in patients on dialysis, and compared to those of healthy controls.METHODWe recruited 59 patients with ESKD [31 patients on haemodialysis (HD) and 28 on peritoneal dialysis (PD)) and 16 healthy controls who received two doses of inactivated SARS-CoV-2 vaccine (V2) from Ramathibodi hospital and Banphaeo General Hospital, Bangkok, Thailand, from July 2021 to September 2021. All participants were administered a third dose of the ChAdOx1nCoV-19 vaccine (V3) with a 6-week interval between the V2 to V3. HIR was measured 2 weeks after V2 and V3 using SARS-CoV-2 immunoglobulin G (IgG) assay, which detects antibodies against the S1 receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Median anti-RBD IgG titer and seroconversion rate, defined as anti-RBD IgG titre ≥ 7.1 BAU/mL, were compared among ESKD patients and to those of healthy controls using the Kruskal–Wallis H test and the chi-squared test, respectively.RESULTSBaseline characteristics of patients on HD, PD and healthy controls are shown in Table 1. Demographic characteristics and baseline laboratory parameters were comparable between the HD and PD groups, except for a lower mean serum albumin level in the PD group (P < .001). None of the healthy controls were immunocompromised or receiving immunosuppressive therapies.Table 1.Clinical characteristics, n (%) HD (n = 31)PD (n = 28)Controls (n = 16)Age, years45 (10)41 (12)41 (9)Male, n (%) 23 (74)17 (61)5 (31)Body mass index, kg/m226 (5)24 (4)27 (6)Charlson Comorbidity Index, median (IQR) 3 (3–5)2.5 (2–4)0Comorbidities, n (%) Diabetes mellitus HypertensionCardiovascular disease 14 (45)24 (77)7 (23) 7 (25)25 (89)2 (7) 1 (6)2 (13)0 Causes of ESKD, n (%) Diabetic nephropathy Hypertensive nephropathy Others Unknown 6 (19)3 (10)5 (16)14 (45) 5 (18)8 (29)8 (29)7 (25)NADialysis vintage, months, median (IQR)33 (17–84)34 (7–57)NATotal Kt/Vurea1.6 (0.3)2.0 (0.4)NALaboratories White blood cells, × 109/L Absolute lymphocyte count, × 109/L Haemoglobin, g/dL Ferritin, ng/mL, median (IQR) Albumin, g/L 6.9 (1.9)1.6 (0.5)11 (2)301 (119–441)40 (4) 7.3 (2.8)1.5 (0.8)10 (2)367 (156–751)33 (4)* 7.7 (2.4)2.2 (0.9)NANANA*P < .05.At 2 weeks after V3, the median anti-RBD IgG titres were significantly increased in all groups compared to those levels after V2 (85[33–412] versus 1566 [861–3083] BAU/mL for patients on HD, 81 [15–144] versus 913 [293–1359] BAU/mL for patients on PD and 250 [92–603] versus 2210 [1531–2782] BAU/mL for healthy controls; P < .001 for all groups). Comparing antibody levels between groups after V3, patients on PD generated significantly lower anti-RBD IgG titer than patients on HD (P = .02) and healthy controls (P < .01) (Figure 1A). The seroconversion rate of the HD and PD groups improved from 94% and 82% after V2 to 100% after V3 in both groups (P = .16 and P = .03, respectively) (Figure 1B). All patients on dialysis who had anti-RBD IgG < 7.1 BAU/mL after V2 (7/59 patients) seroconverted after the additional dose of ChAdOx1 nCoV-19 vaccine. CONCLUSIONWe suggest that an additional ChAdOx1 nCoV-19 vaccine after a primary two doses inactivated SARS-CoV-2 vaccination could improve seroconversion rate and magnitude of humoral immune response in patients on dialysis. The durability of the immune response to this vaccination regimen requires further study.

Inhibition of perforin enhances T cell and humoral responses after immunization

Abstract Cytotoxic lymphocytes such as natural killer (NK) cells release perforin to form pores on plasma membrane of target cells to allow delivery of granzymes that induce apoptosis. We previously showed that NK cells exert a perforin-dependent suppression of follicular helper CD4 T cell and germinal center B cell responses following infection and immunization. Consistent with this activity, genetic ablation of either perforin or NK cells non-additively enhanced the quality and magnitude of humoral immune responses. Therefore, we hypothesize that transient inhibition of perforin represents an innovative means to enhance vaccine efficacy to prevent viral infections such as HIV. Intraperitoneal injection of a selective inhibitor of perforin (35mg/kg) to mice reduced killing activity of NK cells by &amp;gt;50%. A single injection of this inhibitor to mice during alum adjuvanted NP-KLH immunization resulted in a greater than two-fold enhancement of follicular helper CD4 T cell, germinal center B cell, and antigen-specific antibody responses. In summary, transient inhibition of pore-forming protein perforin can block NK-cell immunosuppression to enhance vaccine-elicited T and B cell responses. National Institute of Heath (NIH) (R01-AI148080)

Monitoring of anti-SARS-CoV-2 IgG antibody immune responses in two cohorts of Hungarian healthcare workers following infection or immunization

The length, level and variation of immune responses to infection with SARS-CoV-2 or following anti-SARS-CoV-2 vaccination remains unclear, optimal (re)vaccination protocols remain debated. We investigated the magnitude of humoral immune responses, their over-time changes, the frequency of (re)infections and the association with demographic and clinical parameters in Hungarian healthcare workers. We conducted a prospective, longitudinal study in two groups of healthcare workers of a public, county-level teaching hospital. Cohort 1: The anti-nucleocapsid IgG levels of 42 workers (female: 100%) were followed up over 8 months after SARS-CoV-2 infection (June 2020-February 2021). The change in humoral immune response and its associations with age, existing chronic conditions, blood type and severity of symptoms were investigated. Cohort 2: The anti-spike-RBD protein IgG levels of 49 workers (female: 73%) with no prior COVID-19 infection were monitored over 8 months (December 2020-August 2021) following immunisation with two doses of mRNA vaccine (Pfizer-BioNTech). Analyses included median analysis, linear regression, ANCOVA, Kruskal-Wallis and Skilling-Mack tests. Cohort 1: IgG levels were on average the highest among those in illness severity category 4, the median time of IgG level reduction below the positive test cut-off was 6 months. Cohort 2: The IgG levels increased 25-fold between the first and second immunisations, but decreased to 6% of the peak level after 210 days. They showed an overall negative association with older age and male sex. The suspected levels of (re)infections were 17% and 14% within the infected and the immunised cohorts, respectively, all symptomless. Those affected all worked on high-risk wards. Both the infected and the immunised cohorts showed significantly declining IgG protections beyond 6 months. The average observed rate of (re)infections was 15%, all asymptomatic. Our findings are confirmative of the effectiveness of vaccination to prevent illness, the importance of booster vaccination due to declining humoral immune protection beyond 6 months, and the potential value of anti-SARS-CoV-2 IgG monitoring. Orv Hetil. 2022; 163(12): 455-462.

Longitudinal Study of SARS-CoV-2 Antibody Characteristics Using Label-Free Immunoassays

Abstract Introduction/Objective Since the start of the COVID-19 pandemic, much research has focused on the kinetics and magnitude of humoral immune response. With the advantages of monitoring real-time immunoreactions, label-free immunoassay (LFIA) is becoming a powerful tool in serology studies. We have developed LFIAs to measure SARS- CoV-2 antibody avidity and neutralization activity in a cohort of COVID-19 patients and determine if they correlate with antibody concentration. Serial serum samples collected from mild to severe COVID-19 patients were measured out to 8 months post-symptom onset to determine the durability of the neutralizing antibody response. Methods/Case Report Based on thin-film interferometry technology, we established a label-free IgG avidity assay and a label-free surrogate virus neutralization test (LF-sVNT). For measurement, sensing probes pre-coated with receptor-binding domain (RBD) of SARS-CoV-2 spike protein are applied to serum samples containing SARS-CoV-2 antibodies. The label-free IgG avidity assay measures the binding strength between RBD and IgG under urea dissociation. The LF-sVNT analyzes the binding ability of RBD to ACE2 after neutralizing RBD with antibodies. Results (if a Case Study enter NA) IgG avidity indices and neutralizing antibody titers (IC50) were determined from serum samples (n=246) from COVID-19 patients (n=113). IgG concentrations were measured using a fluorescent immunoassay. The neutralizing antibody titers showed a weak correlation with IgG concentrations and no correlation with IgG avidity indices. Over the time course up to 8 months post-symptom onset, IgG concentrations and neutralizing antibody titers presented similar trends: an initial rise, plateau and then in some cases a gradual decline after 40 days. The IgG avidity indices, in the same cases, plateaued after the initial rise. Conclusion The results demonstrated that LFIA could be used an excellent solution in the determination of SARS- CoV-2 antibody characteristics. The study found that IgG concentration and neutralizing antibody titer declined over time, while IgG avidity index remained constant after reaching a plateau. The decline of antibody neutralization activity can be attributed to the reduction in antibody quantity rather than the deterioration of antibody quality, as measured by antibody avidity.

INFLUENCE OF POLYOXIDONIUM, Poly(I:C), DALARGIN ON THE PROTECTIVE EFFICACY OF YERSINIA PESTIS VACCINE STRAIN EV LINE NIIEG IN EXPERIMENTAL PLAGUE

In this study, the use of immunoadjuvants polyoxidonium (azoximer bromide), Poly (I:C) as a synthetic analog of double-stranded RNA (TLR3 ligand), and synthetic analog of leu-enkephalin dalargin (DA) was experimentally investigated for their potential to minimize ImD50 Yersinia pestis vaccine strain EV line NIIEG co-administrated via invasive (subcutaneous) and noninvasive (intranasal) routes in lethal bubonic and pneumonic models of plague followed by challenge with virulent Y. pestis strains of the main and non-main subspecies from various natural plague foci. The data showed that in all cases immunoadjuvants significantly increased protective efficacy of Y. pestis vaccine strain EV line NIIEG co-administrated to BALB/c inbreed mice in case of lethal challenge with virulent Y. pestis strains in spite of varying magnitude of humoral immune response. Y. pestis vaccine strain EV line NIIEG formulated with polyoxidonium provided more effective protection against lethal challenge with wild-type high virulent strain Y. pestis in pneumonic model of plague. Polyoxidonium introduced into vaccine formula resulted in four-fold rise in total survival in animals with pneumonic plaque. Feasibility of using immunoadjuvants for regimen of specific and urgent plaque prevention is justified.

Refinement of humoral immune monitoring in kidney transplantation: the role of "hidden" alloreactive memory B cells.

The advent of novel sensitive assays assessing circulating anti-human leukocyte antigen (HLA) antibodies has allowed recognizing humoral alloimmunity as the main immune-mediated mechanism responsible for allograft rejection and graft loss in kidney transplantation. However, current immune-monitoring techniques, exclusively focusing on circulating anti-HLA antibodies, may underestimate the magnitude of humoral immune response as they exclude the memory B-cell (mBC) pool. Different biological compartments are involved in the intricate mechanisms triggering humoral alloimmune responses even in absence of detectable circulating alloantibodies. Recent studies in animal models as well as in clinical kidney transplantation have shown the key role of this B-cell subset triggering allograft rejection, thus emphasizing the value of recognizing antidonor mBC both as a biomarker of allosensitization and as therapeutic targets. Therefore, considerable efforts are being made among the transplant research community to better understand the role, hierarchy, and impact of mBC in the context of organ transplantation. In this review article, we provide a deep insight into the biology of mBC as well as main evidence of their role orchestrating allograft rejection. Also, we provide a thorough description of main immune-monitoring tools aiming at tracking mBC and a rational for their potential use to refine current humoral immune-risk assessment in kidney transplantation.

Heterophil/lymphocyte ratios predict the magnitude of humoral immune response to a novel antigen in great tits (Parus major)

Animals display remarkable individual variation in their capacity to mount immune responses against novel antigens. According to the life-history theory, this variation is caused by the costs of immune responses to the hosts. We studied one of such potential costs, depletion of somatic resources in wintering wild-caught captive passerines, the great tits (Parus major) by immune challenging the birds with a novel antigen, killed Brucella abortus (BA) suspension. We found that despite mild temperature conditions in captivity and ad libitum availability of food, immune challenge depleted somatic resources (as indicated by a body mass loss) and elevated relative proportion of heterophils to lymphocytes (H/L ratio) in the peripheral blood of birds. However, body mass loss did not covary with an increase in H/L ratios between two sampling events, which indicates that these two markers of health state describe different aspects of individual physiological condition. Antibody titres were not associated with the extent of body mass loss during the development of immune response, which shows that the somatic cost of immune response was not proportional to the amount of antibody produced. Birds with high pre-immunisation H/L ratios mounted weaker antibody response, which is indicative of stress-induced suppression of humoral immune response and is consistent with the concept of an antagonistic cross-regulation between different components of the immune system. The latter finding suggests a novel diagnostic value of H/L ratios, which reinforces the utility of this simple haematological index for prediction of the outcomes of complicated immune processes.

The adhesion receptor CD155 determines the magnitude of humoral immune responses against orally ingested antigens

CD155, originally known as the cellular receptor for poliovirus, is the founding member of a subfamily of immunoglobulin-like adhesion receptors. Apart from its function in establishing adherens junctions between contacting epithelial cells, the engagement of CD155 with two recently identified ligands, CD226 and CD96, mediates immunologically relevant processes such as NK cell-driven killing of tumor cells in humans. Here we report on the generation and immunological analysis of mice constitutively deficient of CD155. Moreover, the expression profile of CD155 on hematopoietic cells has been determined using newly established antibodies. CD155-deficient mice develop normally without displaying an overt phenotype. However, the animals are distinguished by distinct deficits in the development of a regular humoral immune response. Whereas systemic challenges revealed no differences, orally administered antigen evoked less efficient IgG and IgA antibody responses despite of normal IgM titers when compared to wild-type mice. Therefore, CD155 may assist in an efficient humoral immune response generated within the intestinal immune system.

Absence of interleukin-4 enhances germinal center reaction in secondary immune response

The germinal center (GC) is a compartment for B cell differentiation and proliferation. Interleukin (IL)-4 has been considered essential for GC functioning. To define the role of IL-4 in GC reaction, immunohistology of draining lymph nodes (LNs) of IL-4 gene-targeted (IL-4 −/−) mice was performed during secondary immune response. IL-4 −/− mice were immunized with ovalbumin emulsified in Freund’ complete adjuvant. Final antigen challenge was done 4 weeks later. IL-4 −/− mice had a higher production of IgG2a and IgG2b and a lower production of IgG1 than those in wild-type (WT) mice. In comparison with WT mice, LNs of IL-4 −/− mice on days 4 and 7 after final antigen challenge were larger and contained a markedly greater number of GCs, which showed marked size variations with a large number of small GCs and a small number of markedly large GCs. By day 14, the number of GCs decreased to the same level as that in WT mice. However, the LN size in IL-4 −/− mice was still larger than that in WT mice due to the presence of markedly large GCs. Although well-developed complement receptor(+) follicular dendritic cell (FDC) networks were present in GCs of IL-4 −/− mice, no FDCs of mature phenotype (CD23 +) were observed in many of the small GCs. In conclusion, the absence of IL-4 enhanced GC reaction and specific antibody response of Th1-type. IL-4 may play an important role in inducing the appropriate magnitude of humoral immune response.

Polymorphonuclear neutrophils enhance suppressive activities of anti-CD3-induced CD4 + suppressor T cells

We investigated the effects of polymorphonuclear neutrophils (PMN) on the suppressive activities of CD4 + suppressor T cells induced by immobilized mAb to the CD3 molecular complex in order to explore the role of PMN in the regulation of humoral immune responses. CD4 + T cells that had been treated with mitomycin C induced the IgM production from highly purified B cells in cultures stimulated with immobilized anti-CD3. Addition of CD4 + T cells that had not been treated with mitomycin C (control T4 cells) suppressed the IgM production induced by immobilized anti-CD3-stimulated T4 mito. PMN enhanced the degree of suppression of the IgM production by anti-CD3-stimulated control T4 cells. The capacity of PMN to enhance the suppressive activity of anti-CD3-stimulated control T4 cells was restored when PMN were fixed with paraformaldehyde (PFA), suggesting that direct interactions between PMN and CD4 + T cells, but not soluble factors secreted by PMN, were involved in the enhancement of suppression. Fresh PMN as well as PFA-fixed PMN enhanced the endogenous IL-2 production by immobilized anti-CD3-stimulated CD4 + T cells. Moreover, neither fresh PMN nor PFA-fixed PMN significantly augmented the suppressive activity of anti-CD3-stimulated control T4 cells in the presence of exogenous IL-2. These results indicate that PMN enhance the suppressive activity of anti-CD3-stimulated control T4 cells through direct interactions between PMN and CD4 + T cells. The enhancement of the suppressive activity of CD4 + suppressor T cells by PMN is accounted for by the enhancement of the endogenous IL-2 production by anti-CD3-stimulated CD4 + T cells. Thus, the data demonstrate that PMN influence the magnitude of humoral immune responses by regulating the production of IL-2 through direct interactions with T cells.

Aging and the Immune Response

Abstract Studies were performed to determine the effect of aging on the antibody response and cyst formations after infection with a relatively avirulent strain of the intracellular parasite Toxoplasma gondii. When compared with young mice (4 months), aged mice showed a significant decrease in the magnitude of humoral immune response to infection. This decrease was observed at the peak of the acute infection and also during chronic infection. Evaluation of the presence of Toxoplasma cysts, a measure of the latent infection, revealed that the numbers of tissue cysts present 11 weeks after infection increased with the age of the mice at time of infection. The larger numbers of cysts in older mice which had received the same inoculum size of T. gondii as young mice, together with our previous observations of increased susceptibility of these older mice to T. gondii, suggest that an age-related decrease in the early immune response to this infection allows an increased multiplication of the organism in vivo, leading to increased cyst numbers or death.