Establishment of screening method for effective vaccination using radiolabelled probe

Aiming to develop a screening method for effective vaccination, an investigation was made to establish basic techniques for evaluating cytokine producing abilities of host cells after immunization to mycobacterium leprae. In this study, proliferation of the bacterium was investigated with immunodeficient mice such as BALB/cA-nu/nu, CB-scid, aly/+ and aly/aly and the respective normal mice. When the splenic cells from BALB/cA mouse sensitized with M. leprae (ip, 5 days) was challenged with its cell lysate, γ-IFN was produced, whereas its production was not observed in those from sensitive mouse BALB/cA-nu/nu. In addition, it was suggested that cells which could induce γ-IFN in response to IL-12 were extremely limited in the nude mouse. On the contrary, for IL-18, γ-IFN was inducible in the nude mouse when anti-CD3 was previously coated, indicating that it is difficult to evaluate the efficacy of vaccination only by measuring the productions of IL-12 and IL-18. Therefore, it seems better to determine the amount of γ-IFN protein induced by resensitization with the antigen in the splenic cells. (M.N.)