Figure 8: ALPS patient T cells are defective in Fas-induced differentiation and apoptosis.

(a) Representative data with PBMCs from two unrelated ALPS patients with Fas death domain mutations and a healthy donor control, activated for 7 days with or without FasL-LZ as described in the ‘Methods’ section. Differentiation of CD8⁺ T cells was examined by staining for surface CD27 and CCR7. Cells were gated CD3⁺CD4⁻CD8⁺ before analysis of CD27/CCR7 status. (b) Summary of fold increase in effector memory T cells by FasL-LZ, in seven ALPS patients (N=7) and three normal donor controls (N=3) from two independent experiments. Cumulative data are represented as mean±s.e.m. (c) Cumulative specific cell death induced by FasL-LZ in cell cultures shown in b from two independent experiments. P-values are from an unpaired t-test, with data represented as mean±s.e.m. (d,e) Intracellular staining for pS6 was performed on isolated CD8⁺ T cells from three healthy donors (N=3) and three ALPS patients (N=3), with representative FACS plots (d) shown. Summary of data are shown in e, with fold increase calculated as pS6 MFI vehicle/pS6 MFI FasL-LZ at 20 ng ml⁻¹.