title: Increased density of class I major histocompatibility complex antigens and decreased density of T-cell differentiation antigens in the early stages of T-cell activation.
abstract: Major histocompatibility complex (MHC) antigens and T-cell differentiation antigens on activated T cells play a central role in T-cell interactions. In the present study, we have analyzed time courses of both quantity and density of the T-cell differentiation antigens, CD3 (T3), CD4 (T4), and CD8 (T8), as well as MHC antigens, on the cell surface of T cells, and made correlated measurements of DNA content with the surface antigen quantity as well with RNA content and cell size following activation of T cells by phytohemagglutinin. We found that the quantity and density of class I MHC antigens increase within 24 hr following activation and then decrease, while the quantity and density of the T-cell differentiation antigens decrease within 24 hr following activation, which suggests that T-cell recognition involving class I MHC gene products occurs at an early stage of T-cell activation. Class II MHC antigens can be detected on more than 40% of T cells as the expression of the T-cell differentiation antigens increases much later in the response. Cell cycle studies demonstrated that the density of class I MHC, CD3, CD4, and CD8 antigens was greater in G0/G1 phase cells than G2 phase cells at all times tested during T-cell activation. Our findings suggest that T cells demonstrate a differential regulation in expression of MHC and T-cell differentiation antigens following activation which may reflect their role in cellular interactions.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis*; D002454:Cell Differentiation; D002478:Cells, Cultured; D006680:HLA Antigens / Q000032:analysis*; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D010835:Phytohemagglutinins / Q000494:pharmacology; D012313:RNA / Q000032:analysis; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology* / Q000648:ultrastructure; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D013997:Time Factors
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D006680:HLA Antigens; D010835:Phytohemagglutinins; D012313:RNA