Early kinetics of the PE-specific B cell response. (A) Representative flow cytometry analysis showing the identification of donor CD45.1⁺ PE-specific B cells in the total B cell population (B220⁺, CD11c⁻, Gr-1⁻, and F4/80⁻) in a PE-enriched sample. (B) Representative flow cytometry analysis of CFSE dilution within donor PE-specific cells at the indicated time points after injection and without injection. p.i., post injection. (C) Representative flow cytometry analysis of CD38 and GL7 expression within CFSE^low donor PE⁺ cells at the indicated time points after injection. (D) Combined data from 10 experiments showing the total number of donor PE-specific memory (CD38⁺ GL7⁻), GC (CD38⁻ GL7⁺), and CD38⁺ GL7⁺ populations identified as shown in C, or using CellTrace violet instead of CFSE. The mean and SEM (n = 3–7) are shown for all time points. The mean number of cells in each population calculated in unimmunized mice (n = 8) was considered background and was subtracted from the displayed values. (E) Combined data from 10 experiments showing the total number of recipient (CD45.1⁻) PE-specific GC (CD38⁻ GL7⁺) and CD38⁺ GL7⁺ cells. The mean and SEM (n = 3–14) are shown for all time points.