Intracellular protein expression or functional assays for the index cases from kindreds. (A–F) Flow cytometry study of (A) BTK gated on CD14⁺ monocytes from fresh whole blood from P1 and a control (CTL), (B) SAP in T-blasts from P2 and a CTL, (C) WASp in T-blasts from P3 and a CTL, and (D) DOCK8 in lymphocytes from the fresh whole-blood cells of P4. (E) Degranulation assay on Vγ9⁺Vδ2⁺ T cells stimulated with 1-Hydroxy-2-methyl-2-butenyl 4-pyrophosphate lithium salt (HMBPP) in three CTLs and P5. (F)⁵¹Cr-based cytotoxic activity of Fas-deficient L1210-3 target cells in CD8⁺ T cells from a CTL or P6. The results are expressed as the percent-specific lysis. The effector/target ratio is shown on the x axis and was calculated from the number of CD8⁺ T cells, as determined by flow cytometry.