Figure 7.

gp120 induces FcRL4 via the induction of TGF-β1. (a) Average TGF-β1 ELISA of supernatants from cultured primary B cells from three separate healthy donors stimulated with α-IgM + CpG in presence of an α₄β₇-reactive gp120 (R66M), p<0.0001 (unpaired t-test) (s.e.d. bars) (n=3). (b) FACS analysis of % FcRL4 and % CD80 expression on α-IgM + CpG stimulated B cells in presence of gp120 or TGF-β1. Anti-TGF-β1 was employed to block both gp120-mediated and TGF-β1-mediated effects. The average % of cells expressing FcRL4 and CD80, normalized to FcRL4 and CD80 expression at 96h upon B cell stimulation with α-IgM + CpG alone (100%), p<0.0001(one way ANOVA, Bonferroni Multiple Comparison Test) (s.e.m bars) (FcRL4 n=8) (CD80 n=5). (c) CFSE assay of α-IgM + CpG induced B cell proliferation (1^st panel), in the presence of: an α₄β₇-reactive gp120 (2^nd panel), an α₄β₇-reactive gp120 and an anti-TGF-β1 (3^rd panel), soluble TGF-β1 (4^th panel), and soluble TGF-β1 and an anti-TGF-β1 (5^th panel) of a representative donor. Cells were cultured for 96h. (d) Division Index (FlowJo) indicating the average number of cell divisions in three independent donors, p<0.001 (two-way ANOVA) (n=3). Treatments are listed below the x-axis.