In vivo development of cytolytic T lymphocytes (CTL) to hapten-altered self: MIs-disparate cells facilitate the response by neutralizing IL 2 inhibitor.

Inability to develop CTL in vivo to hapten-altered self can be attributed in part to an inhibitor of interleukin 2 (IL 2) that is present in the serum of normal mice. We have shown earlier that hapten-specific CTL can be generated in C3H mice (H-2k, MIsc) provided CBA/J (H-2k MIsd) spleen cells are injected simultaneously with hapten-modified syngeneic spleen cells into the hind foot paws. In efforts to determine whether serum levels of the inhibitor of IL 2 are altered as a consequence of this successful immunization method, we have compared the activity of the inhibitor in serum at intervals after the injection of syngeneic spleen cells, CBA spleen cells, or TNP-C3H spleen cells alone or together with CBA spleen cells, by using a murine IL 2-dependent, cloned cytotoxic T cell line, CT-6. The results indicate that inhibitor was neutralized optimally 48 to 72 hr after injection of TNP-C3H spleen cells mixed with CBA/J spleen cells. The order in which neutralization occurred was as follows: TNP-C3H cells + CBA/J cells greater than CBA cells greater than TNP-C3H cells greater than normal C3H spleen cells. Furthermore, supernatants from cultures of C3H lymph node cells stimulated in vivo with CBA/J cells also contained IL 2 activity. Thus, injection of CBA/J cells with TNP-modified syngeneic spleen cells produces IL 2 in vivo in sufficient quantity to neutralize the activity of the inhibitor as well as to facilitate the maturation of pre-CTL into hapten-altered self-specific CTL.