Flow cytometric analysis of spleen cell suspensions

from nontransgenic B6 animals (Figure 3B), transgenic B6 CD19-IE mice (Figure 3D), nontransgenic I-A–deficient B6/I-A^−/− littermates (Figure 3C) and their transgenic B6 CD19-IE/I-A^−/− counterparts (Figure 3E). Suspensions were stained with mAbs specific for CD19 (FITC), I-E (PE), and I-A–biotin plus Streptavidin APC. In all 3 color analyses, living cells were first gated according to their FSC/SSC properties and then for their expression of CD19 (Figure 3A). CD19⁺ cells were then further analyzed for expression of I-A and I-E (Figures 3B–E).