ROLE OF T-CELL SUBSETS IN PROTECTION, DELAYED-TYPE OF HYPERSENSITIVITY AND GRANULOMA-FORMATION DURING YERSINIA-ENTEROCOLITICA INFECTION IN MICE

Studies were undertaken with (C57BL/6 x DBA/2) B6D2 F1 mice as a proto type of a strain resistant to Y. enterocolitica. The growth of Y. ente rocolitica in liver and spleen following intravenous infection was det ermined. Restriction of growth of Y. enterocolitica in the spleen and liver started, when a delayed type of hypersensitivity (DTH) became el icitable. Mice were treated with monoclonal antibodies (mAb) specific to T-cell surface markers; injection of these antibodies leads to mark ed depletion of the specific T-cell subset. After selective in vivo de pletion the three characteristic T-cell mediated phenomena, DTH, anti- bacterial protection and granuloma formation were investigated. DTH to Y. enterocolitica soluble antigen was abolished in mice treated with anti-Thy1.2 or anti-CD4 mAbs, while anti-CD8 mAbs had no effect. The e limination of bacteria from the spleens of infected animals was inhibi ted by the application of either anti-Thy1.2 or anti-CD8 mAbs, while a nti-CD4 mAbs had a marginal effect on anti-bacterial protection. The a ccelerated development of mononuclear cell foci in the liver of immune mice was also inhibited by the application of anti-CD4 and anti-CD8 m Abs. Thus, it appears that specific T-lymphocytes play an important ro le in murine Yersiniosis. The present model is valuable for the invest igation of the cellular immune response to this important enteric path ogen.