Murine cytolytic CD8+ T cell clones generated in a high cloning efficiency, accessory cell-free culture system...

To determine whether cytolytic T lymphocyte activity is associated with a particular lymphokine profile, lymphokine synthesis was analyzed in a large panel of primary clones derived from single murine CD8+ lymph node T cells. The clones were generated at high efficiency (60-70%), under conditions that had been optimized for the induction of specific cytolytic activity, by culture with phorbol 12-myristate 13-acetate, ionomycin, IL-2, and IFN-gamma for 6 days and then with IL-2 and IL-6 for a further 2 days. When the clones were restimulated for 24 hr with IL-2 and immobilized antibodies to CD3, CD8, and LFA-1, most secreted IL-3 and IFN-gamma and about a third secreted TNF. Although levels of production of IL-3 and IFN-gamma were positively correlated with each other (r = 0.85) and weakly correlated with cytolytic activity (r = 0.68 and 0.55, respectively). TNF titers were unrelated to any other function measured. None of the clones tested secreted detectable IL-4 or IL-6. Similarly, analysis of several clones for lymphokine mRNA expression following cDNA amplification by the polymerase chain reaction revealed the presence of IL-2, IL-3, IFN-gamma, TNF-alpha, and GM-CSF but not IL-4 or IL-6 transcripts. Cytolytic CD8+ T cell clones generated in this high efficiency, accessory cell-independent cloning system therefore expressed a restricted lymphokine profile characterized by the synthesis of IL-3 and IFN-gamma, with variable production of TNF.