Cytotoxicity of A91V/pLOF cytotoxic lymphocytes. (A) NK-cell cytotoxicity assessed by 51Cr release of peripheral blood mononuclear cells (PBMC) incubated with K562 target cells for 4 hours. The NK-to-target ratio(NK:T) was calculated after flow cytometric quantification of NK cells among PBMC. Spontaneous release was <15%. Experiments were performed in HLH-free episodes of patients with the indicated genotypes in comparison to nonsequenced healthy controls (Ctrl; dark blue). Patient identification numbers are shown in parentheses below the panels. Age of onset of clinical manifestations and phenotype is shown in red next to the panels. (B) CTL cytotoxicity assessed by 51Cr release of phytohemagglutinin/interleukin-2–stimulated T-cell blasts incubated with anti-CD3–labeled L1210 target cells for 4 hours. Cells from patients with the indicated genotypes were analyzed in comparison with nonsequenced healthy ctrl (dark blue). Empty circles: patients with FHL2-related phenotype. Filled circles: asympt individuals. Gray area indicates mean (white line) and 2 standard deviations of cytotoxicity obtained with T cells from healthy ctrl. Asympt, asymptomatic; CTL:T, cytotoxic T cell-to-target ratio; sympt, symptomatic.
