Lytic activity of SAP-deficient CD8⁺ T cells. (A) Lytic activity of EBV-specific CD8⁺ T-cell lines from a SAP-deficient HLH patient (SAP1) and from a healthy control donor. The targets are autologous EBV-transformed B-cell lines used at the indicated effector-target ratio. (B) Mean (± SD) of the lytic activity of allospecific CD8⁺ T-cell lines from 3 SAP-deficient patients (SAP1, SAP2, and SAP3) and from 3 healthy donors (ND1, ND2, and ND3) against the EBV-transformed B-cell line JY. (A-B) ▪ indicates ND; □, SAP deficient. (C) Mean (± SD) of the lytic activity of allospecific CD8⁺ T-cell lines from 3 healthy donors (ND1, ND2, and ND3) against JY cells in the presence of either blocking anti-2B4 mAbs (▨) or isotype control Abs (+IgG1; ▪). (D) Mean (± SD) of the lysis of allospecific CD8⁺ T-cell lines from 3 SAP-deficient patients (SAP1, SAP2, and SAP3) and from 3 healthy donors (ND1, ND2, and ND3) against the CD48^- cell line K562. ▪ indicates ND; □, SAP deficient. One representative experiment of 5 performed is shown. Each mean (± SD) was obtained from 6 data points (3 cell lines studied in duplicate), and statistical analysis was performed using an unpaired t test. Significant differences of lysis between SAP and control T-cell lines are indicated by asterisks (^*P < .05; ^**P < .01).