Lymphocyte chemotactic activity of human interleukin 1

In the cellular immune response, there is an accumulation of mainly nonantigen-specific mononuclear cells that presumably is dependent on the local secretion of chemotactic factors. In view of the presence of large numbers of macrophages early in the delayed hypersensitivity response, the possible role of these cells in the chemotaxis of lymphocytes was investigated by studying the chemotactic activity of purified human interleukin 1 (IL 1) on T and B cells. Chemotactic activity for T and B cells was observed, the effect on B cells being greater than on T cells. At low concentrations (less than 1 U/ml), IL 1 had predominantly chemotactic activity for B cells and chemokinetic activity for T cells. At high concentrations (10 to 20 U/ml), IL 1 had pure chemotactic activity for both cell types. A relationship was found between levels of migration of T and B cells and mouse thymocyte proliferation induced by purified IL 1 and by lipopolysaccharide-stimulated monocyte supernatants. The principal peaks of both activities were found in 16,000 to 18,000 m.w. fractions. In additional studies, the chemotactic response to IL 1 was inhibited by preincubation of T and B cells with IL 1 or stimulated monocyte supernatant, demonstrating the role of binding of IL 1 in the chemotactic response.