Activation of cytotoxic T lymphocytes requires at least two spleen cell-derived helper factors besides interleukin 2.
The dependency of induction of T cell cytotoxicity on lymphokines was studied. 1 X 10(5) nylon wool-purified thymic lymphocytes or 10(4) spleen cells were cultured with TNP-haptenated syngeneic UV-irradiated spleen cells in the presence of a variety of lymphokine preparations. Concanavalin A-induced spleen cell supernatants mediated strong cytotoxic responses in this system. Three other preparations, namely, a partially purified IL 2 preparation from PMA-stimulated EL-4 thymoma cells, a Con A-induced spleen cell supernatant that was absorbed with an IL 2-dependent cell line, and a Con A-induced supernatant that was dialyzed at pH 2 were all ineffective in mediating a cytotoxic response. In reconstitution experiments, cytotoxic responses were only obtained when either the absorbed preparation or the pH 2-treated preparation was mixed with the IL 2 preparation from EL-4 cells. No reconstitution occurred after mixing of the absorbed with the pH 2-treated preparation. pH 2 treatment of the absorbed preparation did not abolish its synergistic effect when added to the IL 2 preparation from EL-4 cells. These results led to the conclusion that activation of cytotoxic lymphocyte precursors requires at least two other lymphokines in addition to IL 2. One T cell cytotoxicity-inducing factor (TCF1) remained in Con A-induced supernatants after absorption with IL 2 receptor-bearing T cell line cells. It was pH 2-resistant and was not found in EL-4 supernatants. A second T cell cytotoxicity-inducing factor (TCF2) was pH 2-sensitive and was found in Con A-induced spleen cell supernatants as well as in interferon-free supernatants of PMA-stimulated EL-4 cells. This activity co-purified with IL 2. It was absorbed by the IL 2-dependent T cell line together with IL 2. IL 2 differs from TCF2 since it is pH 2-resistant.
D000042:Absorption; D000818:Animals; D003208:Concanavalin A / Q000032:analysis / Q000502:physiology; D003602:Cytotoxicity, Immunologic; D006863:Hydrogen-Ion Concentration; D007376:Interleukin-2 / Q000032:analysis / Q000502:physiology*; D008213:Lymphocyte Activation; D008222:Lymphokines; D051379:Mice; D008809:Mice, Inbred C3H; D008811:Mice, Inbred DBA; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D007376:Interleukin-2; D008222:Lymphokines; C021649:concanavalin A-induced helper factors; D003208:Concanavalin A