Differential gene expression in, and production of autoreactive IgM by, human B-cell subsets. (A) Microarray gene expression profiles of sort-purified CD21^lo transitional, CD21^hi transitional, naive, and memory B cells from PB and CB. The range of expression is represented by color shading from black (low expression) to red (high expression). Each column represents 2 pooled donors for the PBMCs and different groups of pooled donors for the CB (range of 2 or 3 different donors for each pooled data). (B) Differential expression of LEF1 and KIA1199 was confirmed by quantitative PCR. Each symbol represents an individual donor (PB, n = 5; CB, n = 2); horizontal lines represent the mean. No values are presented for memory B cells in CB as such cells are infrequent. *P < .05. ***P < .001. (C) B-cell subsets were purified from different healthy donors and cultured with CD40L/IL-21. After 12 days, the amounts of antinuclear IgM antibody were determined. The results are expressed as percentage binding relative to that of the CD21^lo transitional B-cell subset (normalized to equal 100%), and are the mean ± SEM of 5 independent experiments. *P < .05; P < .01; ***P < .001.