title: Membrane-associated interleukin 2 epitopes on the surface of human T lymphocytes.
abstract: Analysis of surface fluorescence with flow cytometry has revealed the presence of membrane-associated interleukin 2 (IL-2) epitopes on the surface of long term human T cell clones. These IL-2 epitopes could not be accounted for by soluble IL-2 binding to its specific receptor or adsorbing nonspecifically to the cells. The level of surface IL-2 antigenic determinants on the T cell clones was decreased in the presence of phorbol esters and increased in the absence of an exogenous source of IL-2. It was completely lost upon stimulation of the clones to produce the soluble lymphokine. Surface IL-2 epitopes were also detected on the Jurkat tumor cell line which secretes IL-2 upon stimulation and on another T cell tumor line MOLT 4. MLA-144 produces IL-2 constitutively; however, it did not possess membrane-associated epitopes. Tumor lines of other lineages were negative. A subpopulation of peripheral blood T lymphocytes demonstrated some membrane-bound IL-2, whereas non-T peripheral blood mononuclear cells were negative. Thus, cells with the potential of producing and secreting IL-2 upon stimulation possessed the surface epitopes of the lymphokine and cells either actively secreting IL-2 or without the potential for secretion were negative for surface expression. Membrane-associated IL-2 antigenic determinants appear to represent a T lymphocytic surface marker of potential cellular function. The relationship of this marker to the secreted lymphokine is not known. Although it is possible that the epitopes seen were present on a distinct molecule independent of secreted IL-2, the distribution on a variety of T cells and regulation via cellular activation suggest that the surface expression of IL-2 epitopes is in some way related to the soluble lymphokine.
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000378:metabolism; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D002999:Clone Cells / Q000032:analysis / Q000378:metabolism; D000939:Epitopes / Q000032:analysis* / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism; D007163:Immunosorbent Techniques; D007376:Interleukin-2 / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000032:analysis* / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000954:Antigens, Surface; D000939:Epitopes; D007074:Immunoglobulin G; D007376:Interleukin-2; C048844:anti-IgG