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

Abstract

Purpose: Limited 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).

Methods: In 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.

Results: A 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 CD21^low 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.

Conclusions: CVID patients with low frequency of switched memory B-cells or an increased frequency of CD21^low 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.

Keywords: CD21low B-cells; COVID-19; CVID; Pfizer-BioNTech BNT162b2 mRNA vaccine; SARS-CoV-2.

Fig. 1

Antibody titers and kinetics in the CVID group compared to healthy controls. A Ab levels for all CVID patients and controls at day 35. The CVID group was divided into 3 subgroups based on their Ab response at day 35: nonresponders (Non-R, <0.4 U/ml), intermediate responders (IM-R, >0.4–250 U/ml), and optimal responders (Opt-R, >250 U/ml). B–D Kinetics of the antibody response in CVID patients and controls at baseline, d10, d21, and d35. Black line designates the median value of each column. (B) In the nonresponder group (n=13), none reached above 0.4 U/ml. C In the intermediate response group (n=25), all patients seroconverted, but none reached the optimal level of 250 U/ml at day 35. D In the optimal response group (n=8), the highest titers were observed in the those who were seropositive at baseline (n=4, open circles), whereas only n=4/42 who were seronegative at baseline reached 250 U/ml at day 35. Red-dotted lines designate the optimal antibody level, defined as the lowest level found in HC

Fig. 2

Lymphocyte profile and B-cell subsets for CVID patients divided in 3 groups based on their vaccine response. A The absolute numbers of CD3⁺, CD4⁺, CD8⁺, NK-, and CD19⁺ cells were defined by FACS analysis. Median values + interquartile ranges are plotted. B B-cell subsets were analyzed by FACS and plotted as % of the total number of CD19⁺ B-lymphocytes. Statistical significance was tested by Mann-Whitney U test. Non-R (n=13): nonresponders; Im-R (n=25), intermediate responders; and Opt-R (n=8), optimal responders. Median values + interquartile range is plotted. C Spearman correlation analysis of antibody titers (U/ml, log 10 units) and CD21^low (% of CD19⁺ B-cells). Red-dotted lines signify the cutoff levels for the 3 different response groups: nonresponders (<0.4 U/ml), intermediate responders (>0.4–250 U/ml), and optimal responders (>250 U/ml). The black line is an estimated correlation curve based on the R value of −0.56 as determined by the Spearman test. Open black circles designate patients with switched memory B-cells <2%. D Vaccine response in different CVID EUROclass groups. CD19, CD19⁺ B-cells; Sw M B, switched memory B-cells; CD21^low, CD21^low B-cells. Statistical significance was tested by the nonparametric Mann-Whitney U test. The red box designates a group of optimal responders: CD19⁺-cells>0.01, Sw M B-cells >2%, and CD21^low < 10%. Black line designates the median value of each column.

Fig. 3

Analysis of absolute numbers of T-cells and relevant subsets in relation to the vaccine response. A Absolute numbers of T-cells in relation to nonresponders (non-R), intermediate responders (IM-R), and optimal responders (Opt-R), as defined in the materials and method section. Red boxes designate significant changes. B Absolute numbers of CD4⁺ effector memory (EM) subsets: Th1, Th2, and Th17 cells in relation to the vaccine response. C Absolute numbers of CD4⁺ central memory (CM) subsets: Th1, Th2, and Th17 cells in relation to the vaccine response. D Stacked data on absolute numbers of CD4⁺ T-cell subsets in relation to the vaccine response. E Stacked data on absolute numbers of CD4⁺ EM T-cell subsets in relation to the vaccine response. F Stacked data on absolute numbers of CD4⁺ CM T-cell subsets in relation to the vaccine response. The Mann-Whitney U test was used to test for statistical significance; p<0.05 was considered to be significant

Fig. 4

Spike IFN-γ and CD4⁺ T-cell responses in patients with CVID and controls. A ELIspot responses for patients with CVID (n=11, red dots) and controls (n=45, black dots) are shown as a dot-plot. Median values are marked with horizontal lines. There was no statistically significant difference between median spot forming units (SFUs) at day 35 between patients with CVID and healthy controls (p=0.77, Mann-Whitney U test). B Spike-specific CD69⁺, CD154⁺, and CD4⁺ T-cell responses for patients with CVID (n=16) and controls (n=44), plotted as % of CD4⁺ T-cells. Patients with CVID had a lower spike-specific CD69⁺, CD154⁺, CD4⁺ T-cell response at day 35, compared to healthy controls (p=0.02, Mann-Whitney U test)