Spleens of allotype chimeras contain normal frequencies of B cell subpopulations. Splenic single cell suspensions from the indicated mouse strains were stained and gated for live, CD4−, CD8−, F4/80− B220+ cells. Further gating was performed as indicated. Frequencies of the gated cells are calculated as percent of total cells within each gate. (Upper) Similar frequencies of immature/transitional (Imm./Tr.). B, marginal zone B (MZ) and B-1 cells are found in spleens of C.B-17 mice and allotype chimeras. (Lower) B220+, CD43+, CD5+ (B-1) spleen cells from chimeric mice express Igha, and B220+, CD43−, CD5− (B-2) cells express Ighb.