FIG 1.

B cells protect hematopoiesis during responses to Pneumocystis lung infection by B cell receptor-independent mechanisms. (A) Total bone marrow (BM) cell counts obtained from lymphocyte-deficient IFrag^−/− and lymphocyte-competent IFNAR^−/− mice over a 16-day course of Pneumocystis murina (PC) lung infection. (B) Total bone marrow count from Pneumocystis-infected IFrag^−/− mice at day 16 postinfection compared to those IFrag^−/− mice in which either splenocytes derived from wild-type (WT) mice, B cell-deficient μMT mice, or splenocytes from mice exclusively expressing a B cell receptor from hen egg lysozyme were adoptively transferred. The results for IFrag^−/− mice in which no cells were transferred (untranferred) are also shown. (C) Relative amount of neutrophils expressed as a percentage of total bone marrow cells analyzed by microscopy from the same groups (no reconst., immune system not reconstituted) displayed in panel B. For statistical analysis of the data in panel A, a two-way ANOVA was performed followed by a Bonferroni posthoc test. For statistical analysis of data in panels B and C, a one-way ANOVA was performed followed by a Tukey posthoc test. Values that are significantly different are indicated as follows: **, P < 0.01; ***, P < 0.001; ###, P < 0.001 when comparing differences between IFrag^−/− and WT spleen versus IFrag^−/− and HELμMT spleen.