Changes in the phenotype of T-cell subset determinants following murine cytomegalovirus infection

The murine model provides a particularly apt experimental system in which to evaluate the effects of cytomegalovirus (CMV) infection. CMV exerts a profound "suppression" of the immune response in the mouse and in humans; the infected animal is no longer able to mediate an appropriate response to mitogens or alloantigens. Using fluorocytometry and fluoresceinated monoclonal antibodies directed against the Thy-1.2, Lyt-1, and Lyt-2 cell membrane determinants following a nonlethal intraperitoneal inoculation of weanling BALB/c mice with Smith strain murine cytomegalovirus, significant changes in T-cell subsets were found that are consistent with findings described in the clinical situation. These ratio changes are temporally consistent with the cytotoxic T-lymphocyte population described by others. Finally, novel changes in the antigenic determinant distribution is found which may reflect the appearance of an antigen-committed cytotoxic T-lymphocyte population. This population which peaks at the ninth postinfection day may consist of 20-47% of the T-lymphocyte population and may offer an explanation for the cellular hyporesponsiveness seen following CMV infection.