Immune-specific gamma interferon production correlates with lymphocyte blastogenesis.

Gamma interferon (IFN-gamma) production, measured by a new commercially available radioimmunoassay, and lymphocyte blastogenesis were investigated in human peripheral lymphocyte cultures from healthy adults stimulated by crude cytomegalovirus (CMV) antigen. Mononuclear cells were obtained from 32 healthy adults (18 CMV seropositive [S+] and 14 CMV seronegative [S-]) by Ficoll-Hypaque gradients and cultured in microtiter plates containing CMV antigen. Lymphocyte blastogenesis ([3H]thymidine uptake) and IFN-gamma were determined on day 6. The mean stimulation index for S+ individuals was significantly greater than that for S- individuals (P less than 0.001). Similarly, the IFN-gamma stimulation index was greater for S+ individuals than for S- individuals (P less than 0.005). A significant increase in the concentration of IFN-gamma (10 NIH units/ml) was observed for S+ individuals at 24 h of antigen stimulation, with peak levels at 4 days. The radioimmunoassay for IFN-gamma production by antigen-stimulated lymphocytes in vitro (IMRX; Centocor Inc., Malvern, Pa.) is a rapid and sensitive measure of cell-mediated immunity.