Figure 1.

Vaccine-induced nAb, B- and T-cell responses to WA1 SARS-CoV-2. Blood was collected from myeloma patients 1 week to 3 months following dose 2 and dose 3 of the SARS-CoV-2 mRNA vaccine. Plasma was analyzed to determine serologic responses to WA1 SARS-CoV-2 using RBD-specific endpoint titer and pseudovirus neutralization assay. Peripheral blood mononuclear cells were examined for the presence of RBD-specific B cells using flow cytometry and single-cell mass cytometry. T-cell response directed against WA1 spike protein was detected using the IFNγ-ELISpot assay as well as antigen-induced marker expression (AIM) assay using cytometry by time of flight (CyTOF). In some patients, immunosequencing of the CDR3 regions of human TCRβ chains was performed using the ImmunoSEQ T-Detect Assay (Adaptive Biotechnologies) to identify SARS-CoV-2–specific T cells. A, Pseudovirus neutralization IC₅₀ following 2 (D2, n = 342) or 3 doses (D3, n = 253). Data, median with a 95% confidence interval (****, P < 0.0001, Mann–Whitney test). B, Pseudovirus neutralization IC₅₀ following 2 (D2) or 3 doses (D3), based on nucleocapsid (NC) Ab reactivity. NC− (D2: n = 269, D3: n = 78), NC+ (D2: n = 73, D3: n = 49). Data, median with a 95% confidence interval (**, P < 0.01; ****, P < 0.0001, Kruskal–Wallis). C, RBD-specific B cells as % of all B cells following dose 2 (D2: n = 107) or dose 3 (D3: n = 60). Figures show median with 95% confidence interval (*, P < 0.05, Mann–Whitney test). D and E, Correlation between RBD-specific B cells and RBD-specific endpoint titer (last dilution for positive assay; D) and pseudovirus neutralization (E). F, RBD-specific IgG⁺ B cells between dose 2 and dose 3 in patients with detectable RBD-specific B cells. Figures show median with 95% confidence interval (*, P < 0.05; Mann–Whitney test). G, CyTOF was performed to examine RBD-specific B-cell response. Hierarchical consensus clustering was performed on RBD-specific B cells from healthy control (HC, n = 7) as well as patients following 2 or 3 doses of the SARS-CoV-2 vaccine (n = 26 and n = 19, respectively). The figure shows FlowSOM map for all samples, as well as a heat map of markers expressed by the four B-cell metaclusters (MC; MC1, MC2, MC3, and MC4). The bar graph shows the proportion of RBD⁺ cells in individual metaclusters. H–J, WA1 spike-specific T cells detected by interferon-γ ELISpot assay. H, IFNγ ELISPOT assay in the entire cohort (dose 2: n = 130, dose 3: n = 60) by dose. I, ELISpot assay split by nucleocapsid reactivity [NC-D2 (n = 100), NC-D3 (n = 35), NC + D2 (n = 22), NC + D3 (n = 25)]. J, ELISpot assay by serum RBD reactivity (seropositive (RBD+ n = 150) and seronegative (RBD− n = 32) nucleocapsid antibody-negative patients. K, Detection of WA1 spike-specific T cells. Graph shows AIM⁺ CD4 and CD8 T cells in patients with detectable spike-specific IFNγ-specific T cells by the ELISpot assay (n = 9) as well as patients who did not have detectable spike-specific IFNγ-specific T cells by ELISPOT assay (n = 2). Pie chart shows the mean proportions of spike-specific CD4⁺ and CD8⁺ T cells for 9 patients with detectable spike-reactive T cells. US = unstimulated control. *, P < 0.05; #, P = 0.05, paired t test. L, Detection of SARS-CoV-2–specific T cells by Adaptive Biotechnologies T-Detect COVID assay. Note that increases in surface glycoprotein-reactive TCRs as assessed by COVID T-cell breadth are mostly seen for CD4⁺ TCRs.