Figure 6. B cell–intrinsic TLR7 drives naive T cell activation, double-negative T cell expansion, and B cell lymphopenia in TLR9-deficient mice.

Flow cytometric analysis was performed on spleens from control (Tlr7^fl/fl Tlr9^–/– and Tlr7^fl/y Tlr9^–/–, solid black circles) and B-Tlr7^Δ Tlr9^–/– (CD19-Cre^+/– Tlr7^fl/fl Tlr9^–/– and CD19-Cre^+/– Tlr7^fl/y Tlr9^–/–, open gray squares) mice. (A–D) Analysis of the B cell compartment in control versus B-Tlr7^Δ Tlr9^–/–, including proportions of B cells as percent of total live cells (A), follicular and marginal zone B cells as a percent of total B cells (B), CD11b⁺CD11c⁺ ABCs as a percent of total B cells (C), and plasmablasts as a percent of total TCRβ^– cells (D). (E–G) Analysis of the T cell compartment in control versus B-Tlr7^Δ TLR9^–/–, including proportions of T cells as a percent of total live cells (E); CD4⁺, CD8⁺, and double-negative (CD4^–CD8^–) T cells as a percent of total T cells (F); and percent naive CD4⁺ and naive CD8⁺ T cells as a percent of CD4⁺ and CD8⁺ T cells, respectively (G). (H–J) Analysis of selected myeloid populations, including proportions of macrophages, monocytes, and neutrophils as a percent of total CD19^–CD11b⁺ cells (H); cDCs as a percent of total CD19^– cells (I); and pDCs as a percent of total CD19^– cells (J). Scatterplots display data from individual mice, with black lines showing median values. *P < 0.05, **P < 0.01, ***P < 0.001, by 1-tailed Mann-Whitney U test.