Fig. 1: Memory B cell repertoire in individuals recovered from COVID-19.

a, b Flow cytometry analysis (a) of the percentages (b) of SARS-CoV-2 RBD-specific memory B cells within the CD19⁺ CD27⁺ memory B cells of the PBMCs from recovered individuals and healthy controls (HC). Freshly isolated PBMCs were stimulated in vitro for 5 days with R848 and IL-2. After 5 days in culture, these cells were plated onto commercial ELISpot plates. c The counts of cells that produced total IgG in per million cultured PBMCs from recovered individuals and healthy controls. d Representative ELISpot dots in recovered individuals and healthy controls. e The counts of cells that produced RBD-specific IgG in per million cultured PBMCs from recovered individuals and healthy controls. f Correlation analysis between RBD-specific ELISpot dot number and virus-specific IgG levels in supernatant after the R848 stimulation on PBMC from individuals recovered from asymptomatic. g Correlation analysis between RBD-specific ELISpot dot number and virus-specific IgG levels in supernatant after the R848 stimulation on PBMC from individuals recovered from symptomatic. Each symbol represents an individual throughout. Data in b, c were analyzed using unpaired, two-sided Mann–Whitney U test, and data in f, g were analyzed using Spearman’s rank correlation test.