Figure 4. CD11a^−/− mice have normal frequencies of LSKs but severe depletion of downstream T cell progenitors in the BM.

(A) BM was isolated from femurs and tibias of adult WT B6 mice and assessed for the expression of CD11a in hematopoietic progenitor cells. Representative histograms show CD11a expression in total lineage negative (Lin⁻) cells compared to the FMO control of Lin⁻ BM cells (left panel). CD11a expression on individual populations of lymphoid progenitors compared to the negative control is shown on the right. Gating strategy for progenitors was as follows: (LSK, Lin⁻Sca-1⁺c-kit⁺; Flt3^highLSKs; CLP, Linc-kit^lo Sca-1^lo Flt3^high CD127⁺). (B–E) BM was isolated from WT and CD11a^−/− mice to compare frequencies of the T cell progenitor populations. Representative zebra plots show LSK (Lin⁻c-kit⁺Sca-1⁺) gating from Lin⁻ cells (B); LSKs were further subdivided into CD127⁺Flt3⁺ and CD127⁻Flt3⁺ cells (C). Lin⁻ BM cells that expressed Flt3 and CD27 (D) were subsequent gated to identify CLPs (Lin⁻ Flt3⁺CD27⁺CD127⁺c-kit^lo/−) (E). The frequencies of each population is shown in the bar graphs (F–I). * p < 0.05 Five animals per group were analyzed in three individual experiments.