Antigen-Specific CD4+ T-Cell Activation in Primary Antibody Deficiency After BNT162b2 mRNA COVID-19 Vaccination

SARS-CoV-2 vaccination in primary antibody deficiencies: an overview on efficacy, immunogenicity, durability of immune response and safety

PURPOSE OF REVIEW

This review aims to summarize the current best knowledge on the efficacy of COVID-19 vaccination in vulnerable patients affected by primary antibody deficiencies (PADs), both in patients previously infected and vaccine-immunized, focusing also on the durability, on the need for multiple booster doses and on the safety of anti-SARS-CoV-2 vaccines.

RECENT FINDINGS

Patients vaccinated for SARS-CoV2 have variable humoral response, still showing a tendency towards an increase in antibody titers, with factors such as booster doses, previous infections, age and specific genetic mutations influencing the outcome. Long-lasting cellular responses to SARS-CoV-2 vaccination instead, mostly of the T-cell type, have been observed. Overall, the duration of protection given by vaccinations is sufficient and increased upon further simulations. Furthermore, the safety profile in PID patients is excellent, with most adverse events being transient and mild and no major adverse event reported.

SUMMARY

Several studies have emphasized the benefit of vaccinating patients with PADs against the SARS-CoV-2 virus and the necessity of administering booster doses. This review, by gathering the most recent and significant data from the scientific literature, could be helpful in clinical practice in the management of disease prevention in patients affected by primary immunodeficiency and also serve as inspiration for further in-depth clinical research.

T-cell activation-induced marker assays in health and disease

Activation-induced marker (AIM) assays have proven to be an accessible and rapid means of antigen-specific T-cell detection. The method typically involves short-term incubation of whole blood or peripheral blood mononuclear cells with antigens of interest, where autologous antigen-presenting cells process and present peptides in complex with major histocompatibility complex (MHC) molecules. Recognition of peptide-MHC complexes by T-cell receptors then induces upregulation of activation markers on the T cells that can be detected by flow cytometry. In this review, we highlight the most widely used activation markers for assays in the literature while identifying nuances and potential downfalls associated with the technique. We provide a summary of how AIM assays have been used in both discovery science and clinical studies, including studies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunity. This review primarily focuses on AIM assays using human blood or peripheral blood mononuclear cell samples, with some considerations noted for tissue-derived T cells and nonhuman samples. AIM assays are a powerful tool that enables detailed analysis of antigen-specific T-cell frequency, phenotype and function without needing to know the precise antigenic peptides and their MHC restriction elements, enabling a wider analysis of immunity generated following infection and/or vaccination.

Impaired B Cell Recall Memory and Reduced Antibody Avidity but Robust T Cell Response in CVID Patients After COVID-19 Vaccination

PURPOSE

Humoral and cellular immune responses were described after COVID-19 vaccination in patients with common variable immunodeficiency disorder (CVID). This study aimed to investigate SARS-CoV-2-specific antibody quality and memory function of B cell immunity as well as T cell responses after COVID-19 vaccination in seroresponding and non-responding CVID patients.

METHODS

We evaluated antibody avidity and applied a memory B cell ELSPOT assay for functional B cell recall memory response to SARS-CoV-2 after COVID-19 vaccination in CVID seroresponders. We comparatively analyzed SARS-CoV-2 spike reactive polyfunctional T cell response and reactive peripheral follicular T helper cells (pTFH) by flow cytometry in seroresponding and non-seroresponding CVID patients. All CVID patients had previously failed to mount a humoral response to pneumococcal conjugate vaccine.

RESULTS

SARS-CoV-2 spike antibody avidity of seroresponding CVID patients was significantly lower than in healthy controls. Only 30% of seroresponding CVID patients showed a minimal memory B cell recall response in ELISPOT assay. One hundred percent of CVID seroresponders and 83% of non-seroresponders had a detectable polyfunctional T cell response. Induction of antigen-specific CD4+CD154+CD137+CXCR5+ pTFH cells by the COVID-19 vaccine was higher in CVID seroresponder than in non-seroresponder. Levels of pTFH did not correlate with antibody response or avidity.

CONCLUSION

Reduced avidity and significantly impaired recall memory formation after COVID-19 vaccination in seroresponding CVID patients stress the importance of a more differentiated analysis of humoral immune response in CVID patients. Our observations challenge the clinical implications that follow the binary categorization into seroresponder and non-seroresponder.

Functional CVIDs phenotype clusters identified by the integration of immune parameters after BNT162b2 boosters

Introduction

Assessing the response to vaccinations is one of the diagnostic criteria for Common Variable Immune Deficiencies (CVIDs). Vaccination against SARS-CoV-2 offered the unique opportunity to analyze the immune response to a novel antigen. We identify four CVIDs phenotype clusters by the integration of immune parameters after BTN162b2 boosters.

Methods

We performed a longitudinal study on 47 CVIDs patients who received the 3rd and 4th vaccine dose of the BNT162b2 vaccine measuring the generation of immunological memory. We analyzed specific and neutralizing antibodies, spike-specific memory B cells, and functional T cells.

Results

We found that, depending on the readout of vaccine efficacy, the frequency of responders changes. Although 63.8% of the patients have specific antibodies in the serum, only 30% have high-affinity specific memory B cells and generate recall responses.

Discussion

Thanks to the integration of our data, we identified four functional groups of CVIDs patients with different B cell phenotypes, T cell functions, and clinical diseases. The presence of antibodies alone is not sufficient to demonstrate the establishment of immune memory and the measurement of the in-vivo response to vaccination distinguishes patients with different immunological defects and clinical diseases.

Monitoring islet specific immune responses in type 1 diabetes clinical immunotherapy trials

The number of immunotherapeutic clinical trials in type 1 diabetes currently being conducted is expanding, and thus there is a need for robust immune-monitoring assays which are capable of detecting and characterizing islet specific immune responses in peripheral blood. Islet- specific T cells can serve as biomarkers and as such can guide drug selection, dosing regimens and immunological efficacy. Furthermore, these biomarkers can be utilized in patient stratification which can then benchmark suitability for participation in future clinical trials. This review focusses on the commonly used immune-monitoring techniques including multimer and antigen induced marker assays and the potential to combine these with single cell transcriptional profiling which may provide a greater understanding of the mechanisms underlying immuno-intervention. Although challenges remain around some key areas such as the need for harmonizing assays, technological advances mean that multiparametric information derived from a single sample can be used in coordinated efforts to harmonize biomarker discovery and validation. Moreover, the technologies discussed here have the potential to provide a unique insight on the effect of therapies on key players in the pathogenesis of T1D that cannot be obtained using antigen agnostic approaches.

Cellular immunity in COVID-19 and other infections in Common variable immunodeficiency

COVID-19 has shed light on the role of cellular immunity in the absence of humoral response in different patient groups. Common variable immunodeficiency (CVID) is characterized by impaired humoral immunity but also an underlying T-cell dysregulation. The impact of T-cell dysregulation on cellular immunity in CVID is not clear, and this review summarizes available literature on cellular immunity in CVID with a particular focus on COVID-19. Overall mortality of COVID-19 in CVID is difficult to assess, but seems not significantly elevated, and risk factors for severe disease mirrors that of the general population, including lymphopenia. Most CVID patients have a significant T-cell response to COVID-19 disease with possible cross-reactivity to endemic coronaviruses. Several studies find a significant but impaired cellular response to basal COVID-19 mRNA vaccination that is independent of an antibody response. CVID patients with infection only have better cellular responses to vaccine in one study, but there is no clear association to T-cell dysregulation. Cellular response wane over time but responds to a third booster dose of vaccine. Opportunistic infection as a sign of impaired cellular immunity in CVID is rare but is related to the definition of the disease. CVID patients have a cellular response to influenza vaccine that in most studies is comparable to healthy controls, and annual vaccination against seasonal influenza should be recommended. More research is required to clarify the effect of vaccines in CVID with the most immediate issue being when to booster the COVID-19 vaccine.

Functionally impaired antibody response to BNT162b2 booster vaccination in CVID IgG responders

BACKGROUND

Although previous studies described the production of IgG antibodies in a subgroup of patients with common variable immunodeficiency (CVID) following messenger RNA vaccinations with BNT162b2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (CVID responders), the functionality of these antibodies in terms of avidity as measured by the dissociation rate constant (k_dis) and the antibody response to booster immunization has not been studied.

OBJECTIVE

We sought to analyze in CVID responders and healthy individuals, the avidity of anti-SARS-CoV-2 serum antibodies and their neutralization capacity as measured by surrogate virus-neutralizing antibodies in addition to IgG-, IgM-, and IgA-antibody levels and the response of circulating (peripheral blood) follicular T-helper cells after a third vaccination with BNT162b2 SARS-CoV-2 messenger RNA vaccine.

METHODS

Binding IgG, IgA, and IgM serum levels were analyzed by ELISA in patients with CVID responding to the primary vaccination (CVID responders, n = 10) and healthy controls (n = 41). The binding avidity of anti-spike antibodies was investigated using biolayer interferometry in combination with biotin-labeled receptor-binding-domain of SARS-CoV-2 spike protein and streptavidin-labeled sensors. Antigen-specific recall T-cell responses were assessed by measuring activation-induced markers by flow cytometry.

RESULTS

After the third vaccination with BNT162b2, IgG-, IgM-, and IgA-antibody levels, surrogate virus-neutralizing antibody levels, and antibody avidity were lower in CVID responders than in healthy controls. In contrast, anti-SARS-CoV-2 spike protein avidity was comparable in CVID responders and healthy individuals following primary vaccination. Follicular T-helper cell response to booster vaccination in CVID responders was significantly reduced when compared with that in healthy individuals.

CONCLUSIONS

Impaired affinity maturation during booster response provides new insight into CVID pathophysiology.

COVID-19 and Inborn Errors of Immunity

Inborn errors of immunity (IEI) are a heterogeneous group of disorders affecting immune host defense and immunoregulation. Considering the predisposition to develop severe and chronic infections, it is crucial to understand the clinical evolution of COVID-19 in IEI patients. This review analyzes clinical outcomes following SARS-CoV-2 infection, as well as response to COVID-19 vaccines in patients with IEI.

Cellular Immune Response to BNT162b2 mRNA COVID-19 Vaccine in a Large Cohort of Healthcare Workers in a Tertiary Care University Hospital

We describe the results of a T-cell immunity evaluation performed after a median elapsed time of 7 months from second-dose BNT162b2 vaccine administration, in a representative sample of 419 subjects from a large cohort of hospital workers. Overall, the Quantiferon SARS-CoV-2 assay detected a responsive pattern in 49.9%, 59.2% and 68.3% of subjects to three different antigenic stimuli from SARS-CoV-2, respectively, with 72.3% of positivity to at least one antigenic stimulus. Potential predictors of cellular response were explored by multivariable analyses; factors associated with positivity to cellular response (to Ag1 antigenic stimulus) were a previous SARS-CoV-2 infection (OR = 4.24, 95% CI 2.34−7.67, p < 0.001), increasing age (per year: OR = 1.03 95% CI 1.01−1.06, p = 0.019 and currently smoking (compared to never smoking) (OR = 1.93, 95% CI 1.11−3.36, p = 0.010). Increasing time interval between vaccine administration and T-cell test was associated with decreasing cellular response (per week of time: OR = 0.94, 95% CI 0.91−0.98, p = 0.003). A blood group A/AB/B (compared to group O) was associated with higher levels of cellular immunity, especially when measured as Ag2 antigenic stimulus. Levels of cellular immunity tended to be lower among subjects that self-reported an autoimmune disorder or an immunodeficiency and among males. Further studies to assess the protective significance of different serological and cellular responses to the vaccine toward the risk of reinfection and the severity of COVID-19 are needed to better understand these findings.

Immunizing the Imperfect Immune System: COVID-19 Vaccination in Patients with Inborn Errors of Immunity

Objective

To update clinicians on current evidence regarding the immunogenicity and safety of coronavirus disease 2019 (COVID-19) vaccines in patients with inborn errors of immunity (IEI).

Data Sources

Peer-reviewed, published studies in PubMed, clinical trials listed on ClinicalTrials.gov, and professional organization and governmental guidelines.

Study Selections

Literature searches on PubMed and ClinicalTrials.gov were performed using a combination of the following keywords: primary immunodeficiency, COVID-19, SARS-CoV-2, and vaccination.

Results

A total of 26 studies met the criteria and were included in this review. Overall, antibody responses to COVID-19 vaccination were found in 72% of study subjects, with stronger responses observed after messenger RNA vaccination. Neutralizing antibodies were detected in patients with IEI, though consistently at lower levels than healthy controls. Risk factors for poor antibody responses included diagnosis of common variable immunodeficiency, presence of autoimmune comorbidities, and use of rituximab. T cell responses were detectable in most patients with IEI, with poorer responses often found in patients with common variable immunodeficiency. Safety of COVID-19 vaccines in patients with IEI was acceptable with high rates of reactogenicity but very few serious adverse events, including in patients with immune dysregulation.

Conclusion

COVID-19 vaccines are safe in patients with IEI and seem to be immunogenic in most individuals, with stronger responses found after messenger RNA vaccinations.

T-Cell Defects Associated to Lack of Spike-Specific Antibodies after BNT162b2 Full Immunization Followed by a Booster Dose in Patients with Common Variable Immune Deficiencies

Following the third booster dose of the mRNA vaccine, Common Variable Immune Deficiencies (CVID) patients may not produce specific antibodies against the virus spike protein. The T-cell abnormalities associated with the absence of antibodies are still a matter of investigation. Spike-specific IgG and IgA, peripheral T cell subsets, CD40L and cytokine expression, and Spike-specific specific T-cells responses were evaluated in 47 CVID and 26 healthy donors after three doses of BNT162b2 vaccine. Testing was performed two weeks after the third vaccine dose. Thirty-six percent of the patients did not produce anti-SARS-CoV-2 IgG or IgA antibodies. Non responder patients had lower peripheral blood lymphocyte counts, circulating naïve and central memory T-cells, low CD40L expression on the CD4+CD45+RO+ and CD8+CD45+RO+ T-cells, high frequencies of TNFα and IFNγ expressing CD8+ T-cells, and defective release of IFNγ and TNFα following stimulation with Spike peptides. Non responders had a more complex disease phenotype, with higher frequencies of structural lung damage and autoimmunity, especially autoimmune cytopenia. Thirty-five percent of them developed a SARS-CoV-2 infection after immunization in comparison to twenty percent of CVID who responded to immunization with antibodies production. CVID-associated T cell abnormalities contributed to the absence of SARS-CoV-2 specific antibodies after full immunization.

Mortality in Severe Antibody Deficiencies Patients during the First Two Years of the COVID-19 Pandemic: Vaccination and Monoclonal Antibodies Efficacy

Patients with severely impaired antibody responses represent a group at-risk in the SARS-CoV-2 pandemic due to the lack of Spike-specific neutralizing antibodies. The main objective of this paper was to assess, by a longitudinal prospective study, COVID-19 infection and mortality rates, and disease severity in the first two years of the pandemic in a cohort of 471 Primary Antibody Defects adult patients. As secondary endpoints, we compared SARS-CoV-2 annual mortality rate to that observed over a 10-year follow-up in the same cohort, and we assessed the impact of interventions done in the second year, vaccination and anti-SARS-CoV-2 monoclonal antibodies administration on the disease outcome. Forty-one and 84 patients were infected during the first and the second year, respectively. Despite a higher infection and reinfection rate, and a higher COVID-19-related mortality rate compared to the Italian population, the pandemic did not modify the annual mortality rate for any cause in our cohort compared to that registered over the last ten years in the same cohort. PADs patients who died from COVID-19 had an underlying end-stage lung disease. We showed a beneficial effect of MoAbs administration on the likelihood of hospitalization and development of severe disease. In conclusion, COVID-19 did not cause excess mortality in Severe Antibody Deficiencies.