Figure 2: Fas C194V is defective in inducing T-cell apoptosis.

(a) Flow cytometry was performed on ex vivo resting and in vitro-activated and cultured CD4⁺ T cells of WT, lpr/+, lpr/lpr or FasC194V^lpr/lpr mice. Grey shaded: isotype control; Black: WT; Green: lpr/+; Blue: lpr/lpr; Red Bold: FasC194V^lpr/lpr. (b) In vitro-activated CD4⁺ T cells from WT, lpr/+, lpr/lpr or FasC194V^lpr/lpr mice were cultured in the presence of increasing amounts of FasL-LZ for 8 h before analysis for apoptosis by flow cytometry. Data are cumulative of six independent experiments and represents the mean specific cell death±s.e.m. (c) Apoptosis of gated effector CD4⁺ T cells (TCRβ⁺B220⁻CD4⁺CD44^hiCD62L^lo) within lymphocytes from the spleen and lymph nodes of WT, lpr/lpr, or FasC194V^lpr/lpr mice were stimulated with FasL-LZ and analysed as in b (N=6). (d) In vitro-activated purified CD4⁺ T cells from the indicated genotypes were stimulated with plate-bound anti-CD3 for 8 h before apoptosis analysis as in (b). Results are compiled from six independent experiments (N=6) and represent the mean specific cells death ± s.e.m. (e) CD4⁺Vβ8⁺ T cells were analysed in 8–10-week-old WT, lpr/lpr, or FasC194V^lpr/lpr mice 6 days after four daily injections of either PBS or 20 μg SEB IP. Data are representative of two experiments, with N≥6 for each genotype. No statistically significant reductions in the percentages of Vβ6⁺CD4⁺ T cells were seen in any genotype. Legend for statistical significance in (b–d): *P≤0.001, WT versus lpr/lpr.⁺P≤0.001, WT versus FasC194V^lpr/lpr. Square: P≤0.001, WT versus lpr/+. Circle: P≤0.001 lpr/+ versus lpr/lpr. Inverted triangle: P≤0.001, lpr/+ versus FasC194V^lpr/lpr. Filled triangle: P≤0.001 lpr/lpr versus FasC194V^lpr/lpr. Unpaired t-test was used for statistical calculations. For (e), NS=not significant, *P<0.05, ****P<0.0001 by Mann–Whitney.