Suppression of B-cell survival and maturation pathways requires the cIAP binding site and RING domain of TRAF2. (A) Structure of TRAF2 protein indicating relevant domains. Flow cytometric analysis of (B) lymph node or (C) spleen cells from mice reconstituted with Traf2ΔB bone marrow transduced with retroviral constructs designed to express the indicated TRAF2 mutants. Mice were also reconstituted with wild-type CD45.1 congenic bone marrow. Plots show data from transduced B cells (CD45.1⁻, B220⁺, GFP⁻, hCD4⁺). (B) Histograms are overlaid on wild-type B cells (CD45.1⁺, B220⁺) from the same chimera. (C) Windows indicate, from left to right: immature (CD21/CD35^lo, CD23^lo), follicular (CD21/CD35^mid, CD23^hi), and marginal zone (CD21/CD35^hi, CD23^lo) B-cell populations. All numbers indicate the proportion of displayed events falling within the associated windows. (B-C) Data are representative of results from at least 3 chimeras (supplemental Figure 2). (D) Survival of transduced Traf2ΔB B cells in vitro. Lymph node cells from chimeras were incubated for 4 days in unsupplemented media. The proportion of input transduced B cells (CD45.1⁻, B220⁺, GFP⁻, hCD4⁺) that survived was calculated and expressed as a fraction of the mean value obtained for vector-transduced B cells. Points indicate duplicate data from individual chimeras mice. Bars represent means. (E) GC differentiation of transduced Traf2ΔB B cells in vivo. Spleens from chimeras were harvested 7 days after SRBC challenge. The proportion of transduced B cells (CD45.1⁻, B220⁺, GFP⁻, hCD4⁺) displaying a GC B-cell phenotype (CD38^lo, Fas^hi) were expressed as a fraction of proportion of wild-type B cells (CD45.1⁺, B220⁺) in the same spleen that possessed the GC B-cell phenotype. (D-E) Data represent pooled results from 2 independent experiments. Points represent data from individual chimeras. Bars represent means.