title: Evidence for an association between CD8 molecules and the T cell receptor complex on cytotoxic T cells.
abstract: The T cell differentiation molecule CD8 is thought to play an important role in class I major histocompatibility complex-restricted T cell activities but the precise function of this molecule is unknown. To explore this question, we have studied several CD3+, CD8+ class I alloantigen-specific cytotoxic T lymphocyte (CTL) lines and clones. The ability of these CTL to proliferate as well as to lyse specific targets was inhibited by either anti-CD3 or anti-CD8 monoclonal antibodies. Exposure of CTL to relevant but not irrelevant target cells induced the rapid (less than 1 hr) disappearance of approximately 20 to 30% of CD3 and CD8 molecules from the cell surface. The modulation of these molecules became maximal at 6 to 12 hr and recovered thereafter in parallel. Treatment of CTL with anti-CD8 prevented alloantigen-induced modulation of CD3, and treatment with anti-CD3 blocked modulation of CD8. Incubation of CTL with the combination of anti-CD3 and goat anti-mouse Ig also resulted in modulation of CD8. In contrast, the expression of other CTL surface antigens, such as CD2 (Leu-5, T11) and HLA-DR, was not reduced by any of these manipulations. These results suggest that CD8 molecules are associated with the CD3/antigen receptor complex on the surface of CTL, and may play a direct role in antigen-induced modulation and cross-linking of the T cell receptor.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis* / Q000276:immunology; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008934:Mitogens / Q000494:pharmacology; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D013602:T-Lymphocytes, Cytotoxic / Q000032:analysis* / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D008934:Mitogens; D011948:Receptors, Antigen, T-Cell