Expression of Bcl-2 and survival of human B-cell subsets. (A) Microarray of survival genes expressed by PB and CB CD21^lo transitional, CD21^hi transitional, naive, and memory B cells. The range of expression is represented by shading from black (low expression) to red (high expression). Each row corresponds to a different probe for the indicated gene of interest. (B) MNCs from CB, PB, and spleen were stained with anti-CD20, -CD27, -CD10, and -CD21 mAbs to identify transitional, naive, and memory B-cell subsets. The cells were then fixed, permeabilized, and incubated with anti–Bcl-2 (black line) or isotype control (gray filled) mAb. The values in each histogram represent the ratio of MFI of cells incubated with anti-Bcl-2 mAb over that of cells incubated with an isotype control ± SEM (CB, n = 4; PBMCs, n = 11; spleen, n = 9). (C-D) CD21^lo transitional, CD21^hi transitional, naive, and memory B cells purified from PB (C top left panel) or spleen (C top right panel) were cultured in media alone (C), or with (D) BAFF (0.5 μg/mL; left panel) or F(ab′)₂ fragments of anti-Ig (2.5 μg/mL; right panel) for 100 hours. The number of viable cells was determined at the indicated times. Results shown are the mean ± SEM of 3 independent experiments for PBMCs and 2 independent experiments for spleen.