title: Is there an interleukin 2 inhibitor in human serum?
abstract: Normal mouse serum has been shown to contain an inhibitor of interleukin 2 (IL-2). Here we report that a molecule with similar activity cannot be found in normal human serum (NHS). Although NHS inhibited the IL-2-dependent proliferation of mouse CTLL cells, as expected of an IL-2 inhibitor, it also had inhibitory activity on IL-3-dependent cells and was cytolytic to IL-2-independent mouse cells as measured by a 51Cr release assay, indicating a nonspecific effect. In addition, NHS had no effect on the IL-2-dependent proliferation of human peripheral blood T-cell blasts. Fractionation of NHS by size exclusion HPLC failed to separate cytolytic activity from any putative true IL-2 inhibitor activity. The cytolytic component was not related to immunoglobulin since it had a molecular weight of 50,000 to 60,000 and was not bound by protein-A-Sepharose. However, its molecular weight, heat lability, and trypsin sensitivity suggest it to be a protein.
mesh_terms: D001798:Blood Proteins / Q000302:isolation & purification / Q000502:physiology*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D003603:Cytotoxins / Q000097:blood*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007376:Interleukin-2; D008213:Lymphocyte Activation; D008970:Molecular Weight; D011971:Receptors, Immunologic / Q000502:physiology; D015375:Receptors, Interleukin-2; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D001798:Blood Proteins; D003603:Cytotoxins; D007074:Immunoglobulin G; D007376:Interleukin-2; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2