Intrahepatic alpha beta-TcRintermediate LFA-1high T cells are stimulated during mouse hepatitis viral infection.

Mouse hepatitis virus type 3 (MHV3), a coronavirus, is an excellent animal model for the study of thymic and extrathymic T cell subpopulation disorders induced during the viral hepatitis. To understand local hepatic immune responses, the phenotypes of resident hepatic lymphocytes were determined and compared that of splenic and thymic T cell subpopulations during the acute viral hepatitis induced by MHV3 in susceptible C57BL/6 mice. Single positive (SP) CD4+ or CD8+ cells strongly increased in the liver. A specific cell population, the double positive (CD4+ C8+) cells, normally present in liver and thymic cell preparations, decreased in C57BL/6 mice following the viral infection. alpha beta-TcRintermediate T cells shifted toward alpha beta-TcRhigh T cells in the liver and thymus of infected mice, but not in their spleen. The specific alpha beta-TcRint or high lymphocytes occurring in the liver of MHV3-infected mice expressed higher levels of leukocyte function antigen-1 (LFA-1) and Pgp-1 (CD44) activation markers, suggesting that they were either activated or antigen-experienced during the viral infection. No significant changes in T cell subpopulations were detected in the spleen. These observations suggest that MHV3 infection could induce an early in situ stimulation of resident hepatic T cells, despite a peripheral immunodeficiency in the thymus and spleen.