Detection of antigen-specific cellular immune response by the in vitro production of T-cell growth factor

The amount of T-cell growth factor (TCGF) produced in vitro in antigen-stimulated lymphocyte cultures was measured by induction of growth in cell lines dependent on the factor. The method distinguished eight herpes-simplex-seronegative subjects from ten seropositive ones, and these results correlated with those of the lymphocyte blast transformation (LBT) test. The LBT responses and TCGF amounts produced in cultures with purified tuberculin (PPD) were also in good correlation (r = 0.833, P less than 0.001). Considerable levels of the factor were already present 12 h after the beginning of the culture. The method offers rapid quantification of cell-mediated immunity to specific antigens.