THE CELLULAR IMMUNE-RESPONSE AGAINST YERSINIA-ENTEROCOLITICA IN DIFFERENT INBRED STRAINS OF MICE - EVIDENCE FOR AN IMPORTANT ROLE OF T-LYMPHOCYTES

Resistance of mice against infection with Yersinia enterocolitica has been shown to be related neither to the Ity locus coding for resistanc e against infection with Salmonella typhimurium and other pathogens no r to the H-2 locus. From other mouse infection models, e.g., murine le ishmaniasis, there is evidence that a different T cell-dependent regul ation of the host immune response in various inbred strains of mice de termines the susceptibility to the infectious agent. However, until re cently, little was known about the cellular immune response against Y. enterocolitica. Thus, in a first approach we used the highly virulent Y. enterocolitica strain WA of serotype 0:8 and different inbred stra ins of mice (C57 BL/6, Balb/c and athymic T cell-deficient C57 BL/6 nu de mice) to investigate the cell-mediated immunity against parenteral infection. Comparison of the median lethal dose and of the net-bacteri al growth in the spleens of infected mice indicated that Balb/c mice c ould be considered as Yersinia-susceptible whereas C57 BL/6 mice were relatively resistant. However, in contrast to normal C57 BL/6, athymic T cell-deficient C57 BL/6 nude mice have proved to be highly suscepti ble to Yersinia infection suggesting that T cells are required for the elimination of the pathogen. This conclusion was supported by histomo rphological and immunohistological results indicating that T lymphocyt es were present in Yersinia-induced tissue lesions. Moreover, the adop tive transfer of Yersinia-specific T cell lines and clones into naive animals mediated significant protection against the pathogen in both Y ersinia-resistant C57 BL/6 and in Yersinia-susceptible Balb/c mice. Th ese findings emphasize an important role of T lymphocytes in the host response against Y. enterocolitica infection.