Antigen-specific cytotoxicity is dramatically increased after overnight culture in IL-2, which also restores CD3ζ expression.
(A) PBMC from subject AI-1, obtained 19 days after the onset of symptoms, were tested for specific cytotoxicity in a 4-hour51Cr release assay against autologous EBV-transformed B-LCL. PBMC were either uncultured (♦) or cultured with (▴) or without (▪) added IL-2 (600 IU/mL). Overnight culture in IL-2 did not induce lysis by preinfection samples. (B) The enhanced cytotoxicity detected after overnight culture in IL-2 is predominantly antigen-specific. Cytotoxicity of fresh or cultured day 19 PBMC was assayed at an E:T ratio of 20:1 against autologous AI-1 B-LCL and against B-LCL from 2 normal donors, who did not share HLA class I alleles with subject AI-1. (C) Histograms of CD3ζ expression on gated CD4+ and bright CD8+ cells. The solid line depicts uncultured cells, the dotted line represents the cells cultured in the absence of IL-2, and the filled histogram denotes cells cultured in IL-2. Before culture, CD3ζ expression on virtually all CD4 T cells is above background B-cell staining. After culture in IL-2, the mean fluorescence intensity of CD8 T cells becomes comparable to that of CD4 T cells.
