Perforin is dispensable for Vγ9Vδ2 antiparasitic activity. A Vγ9Vδ2 T-cell line was generated from a perforin-deficient familial hemophagocytic lymphohistiocytosis (FLH) patient, and its antiparasitic activity was assessed in a standard parasite inhibition assay. (A) Flow cytometry histograms showing perforin and granulysin expression in Vγ9Vδ2 T-cell lines generated from 2 different donors (S1 and JT) and from an FLH patient (PFNdef). Mean fluorescence intensity (MFI) for perforin and granulysin intracellular staining is indicated in the top right corner of each panel. Dotted lines represent isotype control antibody. (B) Comparison of the antiparasitic activity of the PFNdef, S1 and JT cell lines. The αβ T4A.5 T-cell clone was used as a negative control. Antiparasitic activity (percentage) was calculated as 100 − [(average % parasitemia of duplicate with cells in the presence of IL-2 + IL-15/average % parasitemia of duplicate with cells in the presence of IL-2) × 100]. Data represent the mean ± SD of 4 independent experiments (n = 4; *P ≤ .05 by Mann-Whitney rank sum test comparing the PFNdef cell line with the S1, JT, or T4A.5 T-cell lines).