Figure 6. IL4RA expression by FDCs limits IL4 availability to GC B cells.

(A) Violin plots of Il4ra and Epcam expression in different stromal cell subsets. (B, C) Representative FACS profiles (B) and histograms (C) of IL4RA in non-FDCs (CD45⁻ PDPN⁺ CD31⁻ CD21/35⁻ EPCAM⁻) and FDCs (CD45⁻ PDPN⁺ CD31⁻ CD21/35⁺ EPCAM⁺) isolated from mesenteric LNs in mice with indicated genotype. Data represent two experiments, with at least three mice per experiment. (D-G) Reverse chimaeras were made by reconstituting irradiated Il4ra^+/+ and Il4ra^−/− mice with WT BM. (D-F) Frequencies of CD95^hi GL7^hi GC B cells in B220⁺ IgD⁻ B cells (D), CXCR4^lo CD86^hi LZ cells in GC B cells (E left), CD23⁺ cells in LZ B cells (E middle), CD31⁺ cells in CD23⁺ LZ B cells (E right) and IgG1⁺ cells in GC B cells (F) 13 days after immunization. (G) Ratio of CD73⁺ IgG1⁺ memory B cells to IgG1⁺ cells. Data are pooled from three experiments. (H-M) Reverse chimeras were made by reconstituting irradiated control and Cd21^Cre/+ Il4ra^f/f mice with wild-type (Il4ra^+/+) BM. (H-K) Frequencies of CD95^hi GL7^hi GC B cells in CD19⁺ B cells (H), IgG1⁺ cells in GC B cells (I), LZ cells in GC B cells (J left), CD23⁺ cells in LZ B cells (J middle), CD31⁺ cells in CD23⁺ LZ B cells (J right) and CD31⁺ CCR6⁺ cells in GC B cells (K) 13 days after immunization. (L, M) Frequencies of NP⁺IgG1⁺ (L) and CD73⁺ IgG1⁺ (M) memory cells in non-GC B cells. (N-P) Scheme for testing memory response in Ccl19^Cre/+ Il4ra^f/f mice that had been reconstituted with wild-type BM (N), flow cytometry plots from the indicated mice (O), and summary data (P) showing frequency of CD138⁺NP⁺ plasma cells in the spleen of boosted control or Ccl19^Cre/+ Il4ra^f/f chimeric mice. Data are pooled from two of three experiments. In D-M and P, each symbol represents one mouse. See also Figure S6.