Figure 1.

Costimulatory molecules required for in vitroLat^Y136F T cell mediated B cell activation. (A) Expression of costimulatory molecules on the surface of WT (gray) and Lat^Y136F (solid line; CD8/CD4) lymph node T cells investigated by flow cytometry. (B) FACS analyses of lymph node from WT and LAT mutant mice using CD4 and B220. The frequency of T_FH defined as PD-1⁺ CXCR5⁺ was also investigated among CD4 positive T cells. (C) IgG₁ secretion was investigated by ELISA 6 days after in vitro culture of Lat^Y136F CD4 T cells in the presence of WT splenocytes or of splenocytes deficient for the specified costimulatory molecules. Data are representative of at least three independent experiments. (D) Effects of blocking antibodies on IgG₁ secretion were assessed by ELISA 6 days after co-culture of Lat^Y136F CD4 T cells and of WT splenocytes. Bar graph corresponds to mean ± SD from three independent experiments. Mann Whitney test was performed to determine whether differences were significant. *p-Value < 0.1; **p-value < 0.05.