Evaluation of the induction of specific cytotoxic T lymphocytes following immunization of F1 hybrid mice with rabies antigens

The measurement of the production of cytotoxic T lymphocytes (CTL) induced in mice by rabies antigens currently uses spleen cells from immunized A/J mice as effector cells and infected neuroblastoma syngeneic cells as target cells. For several reasons, including difficulties in obtaining A/J mice, as well as genetic analysis of immune responses, it would be advantageous to use strains of mice other than the A/J mice. However, cell lines other than the neuroblastoma Neuro-2a line are difficult to infect by the rabies virus. Therefore, using the same target cells expressing the major histocompatibility complex H-2kd, we have developed an experimental system based on the induction of CTL in F1 BALB/c X C3H/HeJ hybrid H-2kd mice. Splenocytes from F1 hybrid mice primed with inactivated purified rabies virus (IPRV) exhibited cytotoxic activity specific for syngeneic infected target cells (Neuro-2a). High amounts of IPRV were required for the induction of CTL following in vivo priming. The antigen dose required for CTL induction was reduced by in vitro restimulation. In addition to specific CTL, a high level of natural killer cell activity was induced in F1 hybrid mice by priming with IPRV. Among rabies antigen preparations tested (IPRV, purified glycoprotein and ribonucleoprotein), only IPRV induced strong CTL stimulation.