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. 2021 Nov 20;224(11):1861–1872. doi: 10.1093/infdis/jiab535

Figure 1.

Figure 1.

GC-dependent immunity in convalescent patients. A, SARS-CoV-2 spike protein (S1+S2)-specific IgM, IgG, and IgA responses: red and black data points/lines show the results for plasma from convalescent samples (n=21) and healthy control samples (collected before the COVID-19 outbreak; n=12), respectively. B, Neutralization is indicated according to plasma dilution at the indicated dpi. The SARS-CoV-2 plaque reduction was 50%. C, Representative ELISPOT data of SARS-CoV-2 spike protein (S1+S2)-specific IgM (blue) and IgG (red) ASCs in human PBMCs. Circles represent individual data and the line represents mean (unpaired Student t test; ∗∗P<.01). Data are presented as mean ± SEM. D, Frequency of MBCs in PBMCs from healthy and convalescent samples. Representative ELISPOT data of SARS-CoV-2 spike protein (S1+S2)-specific IgM (blue) and IgG (red) ASCs differentiated from MBCs over 4 days using anti-CD3 and anti-CD28 monoclonal antibodies (1 μg/mL). Circles represent individual data and the line represents mean (unpaired Student t test; ∗∗P<.01). Data are presented as mean ± SEM. Abbreviations: ASC, antibody-secreting cell; COVID-19, coronavirus disease 2019; dpi, days postinfection; ELISPOT, enzyme-linked immunospot; GC, germinal center; Ig, immunoglobulin; MBC, memory B cell; OD, optical density; PBMC, peripheral blood mononuclear cell; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.