Description of phenotypically distinct T-lymphocyte subsets which mediate helper/DTH and cytotoxic functions in the Syrian hamster.

Recent studies describe aberrations in the functions of T lymphocytes from Syrian hamsters. A current proposal links the apparent functional deficiencies of cytotoxic and suppressor T cells with anomalies found in class I molecules of this species (no polymorphism is detected) and speculates that hamsters possess limited heterogeneity of T cell subpopulations, particularly a class I-restricted subset. The present work tests this hypothesis by examining the extent of T cell heterogeneity defined by differential cell surface antigen expression. A panel of mouse monoclonal antibodies against hamster lymphocyte antigens was generated. MAb #20 and #110 bound to most, if not all, peripheral T cells; a third antibody, #38, divided T cells into two subpopulations which were functionally distinct. Cells within the #38-negative subset produced easily detectable IL 2 and mediated delayed-type hypersensitivity to influenza virus. In contrast, isolated 38+ cells produced little IL 2 and required the addition of exogenous T cell growth factor for proliferation to Con A. Treatment of immune cells with mAb #38 and complement abrogated cytolysis to TNP-haptenated or influenza-infected targets. Thus, Syrian hamsters possess at least two T cell subpopulations of discrete functional ability and unique cell surface antigen expression. Although the data suggest that T cells analogous to those of the class I-restricted, Lyt 2+ subset are present in the hamster, it is predicted that the scope of their composite antigen receptor repertoire may be limited by the monomorphism of class I molecules in this species.