INTERFERON-GAMMA PRODUCTION IN ANTIGEN-SPECIFIC T-CELL RESPONSE - QUANTITATION OF SPECIFIC MESSENGER-RNA AND SECRETED PROTEIN

Interferon gamma (IFN-gamma) production as a measure of cellular sensi tization was studied by detection of the cytokine in culture supernata nt by enzyme immunoassay (EIA) and by measuring cellular mRNA using th e reverse transcriptase polymerase chain reaction (RT-PCR) method, The se assays were compared to the standard lymphocyte proliferation assay as a marker of T cell responsiveness to foreign antigens. When blood donors seropositive for herpes simplex virus (HSV) were compared to se ronegative donors, all measurements of cellular sensitization separate d the groups without overlap. There were significant correlations betw een the IFN-gamma mRNA titre and the secreted IFN-gamma (r = 0.57, P = 0.03), and the proliferative response and the secreted IFN-gamma (r = 0.78, P = 0.001), as well as between the IFN-gamma mRNA titre and the proliferative response (r = 0.78, P < 0.001). When tetanus toroid (TT ) responses were studied in immunized subjects, a wide range of respon siveness could be seen and correlation between various measurements wa s poor. However, constant individual levels of the cytokine production were demonstrated. Six people who had received their last TT booster vaccination more than 5 years ago were revaccinated and repeatedly stu died. An increase in the levels of produced IFN-gamma could be seen in all subjects and two who lacked a lymphocyte proliferation response d eveloped it after revaccination.