title: Activated T cells and monocytes have characteristic patterns of class II antigen expression.
abstract: The expression of human histocompatibility class II Ag was measured on activated T cells and monocytes by quantitative mAb binding in direct two-color immunofluorescence. Monocytes activated by IFN-gamma bound an average of 2 x 10(6) DR-specific mAb, 3 x 10(5) DQ-specific mAb, and 7 x 10(5) DP-specific mAb per cell. For T cells activated by anti-CD3, a subpopulation bound 1 x 10(5) DR-specific mAb, 5 x 10(4) DQ-specific mAb and 5 x 10(4) DP-specific mAb per cell. These measurements were obtained after establishing a base line of class II Ag expression on resting B cells and monocytes. Resting B cells and those monocytes that were positive for class II Ag bound identical amounts of mAb; 3 x 10(4) DR-specific mAb, 3 x 10(3) DQ-specific mAb and 2 x 10(4) DP-specific mAb. However, most resting monocytes (75%) expressed only DR Ag. In the process of studying the expression of class II Ag on T cells, it was necessary to define and analyze the activated T cell state. Cell cultures activated with 0.3 ng/ml anti-CD3 had the highest expression of class II Ag on T cells, whereas those activated with 3.0 ng/ml anti-CD3 had the highest expression of IL-2R on T cells. Addition of IL-2 had no further effect on DR Ag expression on T cells but did up-regulate IL-2R expression. Reducing the initial monocyte concentration before activating T cells increased class II Ag expression on T cells without affecting IL-2R expression. The results obtained on T cell activation suggest that perhaps a lymphokine may be made by CD3-activated T cells which induces class II Ag expression on T cells.
mesh_terms: D000911:Antibodies, Monoclonal; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D006681:HLA-D Antigens / Q000032:analysis*; D006682:HLA-DP Antigens / Q000032:analysis; D006683:HLA-DQ Antigens / Q000032:analysis; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D007399:Interphase; D008213:Lymphocyte Activation; D008262:Macrophage Activation; D009000:Monocytes / Q000032:analysis* / Q000276:immunology / Q000502:physiology; D010641:Phenotype; D013601:T-Lymphocytes / Q000032:analysis* / Q000145:classification / Q000276:immunology; D013861:Thiocyanates
chemical_list: D000911:Antibodies, Monoclonal; D005452:Fluoresceins; D006681:HLA-D Antigens; D006682:HLA-DP Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D013861:Thiocyanates; D016650:Fluorescein-5-isothiocyanate