Use of a radioactive double labeling technique in the chemical analysis of the mediators of cellular immunity.

Radioactive double labeling was adapted for the analysis of mediators of cellular immunity. Two identical lymphocyte cultures were simultaneously labeled with [3H]- or [14C]leucine. Each of the cultures was stimulated with antigen or mitogen. The combined supernatants were then subjected to various fractionation procedures. By determining the isotope ratio in each fraction it is possible to identify those products of activated lymphocytes that have been produced either de novo or in increased amounts. The method proved sensitive enough to detect lymphocyte activation products in supernatants of activated lymphocyte cultures from guinea pig, mouse, and man.