Analysis of experimental interassay variability in evaluation of cytotoxic lymphocyte exocytosis. (A) PBMCs from 198 healthy adult volunteers were incubated for 3 hours in medium or with target cells and monoclonal antibodies (mAbs) as indicated. Induced CD107a surface expression (ΔCD107a) values for distinct cytotoxic lymphocyte subsets and stimulations, as indicated, in 198 healthy adult volunteers. Graph depicts mean values with bars indicating standard deviation (SD). (B-F) Compiled induced CD107a surface expression values for distinct cytotoxic lymphocyte subsets and stimulations, as indicated, from 2 healthy adult volunteers run 17 (donor 1) and 23 times (donor 2) using multiple frozen PBMC vials thawed over a period of 3 months. Samples were run using the same exocytosis protocol. Shown are the ΔCD107a for CD3^–CD56^dim NK cells after K562 or anti-CD16 stimulation and CD8⁺CD57⁺ T cells (CTL) after anti-CD3 stimulation. Results plotted against time for donor 1 (B) and donor 2 (C), displaying results of the 3 different exocytosis stimulations. The same data were normalized by dividing each value by respective mean and plotted against time for donor 1 (D) and donor 2 (E), demonstrating the range of deviation for each assay and donor. (F) Accumulated normalized data for each assay. Bars indicate SD.