Functional studies of T lymphocytes and neutrophils. (A) Time course of induced apoptosis in STK4-deficient T cells on exposure to anti-Fas, which was measured by staining with annexin-V and propidium iodide. STK4-deficient T cells exhibited a significantly higher degree of apoptosis than did cells from control or heterozygous persons. (B) Time course of induced apoptosis in STK4 neutrophils on exposure to staurosporine. Patients' neutrophils showed increased apoptosis compared with healthy persons. (C) Visualization of gradual loss of mitochondrial membrane potential evidenced by fading CMXROS fluorescence intensity in T cells. Note that patients P1 and P2 have accelerated loss of Δψm compared with healthy control cells. (D) Enhanced loss of mitochondrial membrane potential Δψm in STK4-deficient neutrophil granulocytes, which is measured by fading JC-1 dye fluorescence intensity. (E) Decreased FOXO3 expression in PBMCs of STK4-deficient patients revealed by Western blot. Both the apoptosis and mitochondrial membrane potential assays were done twice, on independently purified cells.