Figure 3.

S_167–180 response in peripheral blood following BNT162b2 vaccination

(A) Representative flow cytometry plots of S_167–180 tetramer staining following vaccination of subject 04. Frequency displayed is the percent of live CD3⁺CD4⁺ T cells in the blood that are tetramer positive.

(B) The frequency of S_167–180 tetramer⁺ cells in the blood over time in 8 of the study subjects with available PBMC from most time points.

(C–F) Surface phenotype of circulating S_167–180 tetramer⁺ cells over time. Representative flow cytometry overlay plots from subject 04 showing total CD4⁺ T cell (gray contours) and tetramer-positive (red contours) populations. (C) The majority of S_167–180 tetramer⁺ cells retain an “effector memory” (CD45RO⁺CCR7^-) surface phenotype following vaccination. (D) A subset of S_167–180 tetramer⁺ cells undertake an “activated” surface phenotype (HLA-DR⁺CD38⁺) in the 2 weeks following vaccination. (E) ICOS and PD-1 are upregulated on the majority of S_167–180 tetramer⁺ cells prior to and 7 days following boost vaccination. (F) A small subset of S_167–180 tetramer⁺ cells undertake a “circulating T_FH” surface phenotype (CXCR5⁺PD1⁺) following boost vaccination, but the majority of circulating S_167–180 tetramer⁺ cells do not exhibit this phenotype.

(G) S_167–180 tetramer⁺CXCR5⁺PD1⁺ cells as a percentage of total live CD3⁺CD4⁺ T cells over time.