Both interleukin 2 and a second T cell-derived factor in EL-4 supernatant have activity as differentiation factors in IgM synthesis.
B cells cultured with anti-IgM, BSF-p1, and B15-TRF will differentiate into high rate IgM-synthesizing cells in the presence of supernatants from EL-4 cells that have been induced with phorbol myristate acetate. These supernatants contain two molecular species (EL-TRFs) that have differentiative activity. One co-migrates with interleukin 2 (IL-2) and its activity is blocked by antibody to the IL-2 receptor. Furthermore, molecularly cloned IL-2, at concentrations of 100 U/ml or more, expresses such EL-TRF activity. The EL-TRF activity of cloned IL-2 can also be inhibited by antibody to the IL-2 receptor. The other material with EL-TRF activity has a molecular weight of approximately 32,000. This material lacks IL-2 activity. Antibody to the IL-2 receptor does not impair its function. B cells stimulated with anti-IgM and BSF-p1, with or without B15-TRF, express determinants that react with two monoclonal antibodies which recognize distinct epitopes on the T cell IL-2 receptor. These determinants are present at much lower density (approximately 100-fold) on stimulated B cells that on HT-2 cells, an IL-2-dependent T cell line. Very small amounts of [3H]IL-2 (less than 1,000 molecules per cell) bind to activated B cells. These results indicate that IL-2 binds to a receptor on appropriately prepared B cells and causes them to differentiate into high rate IgM-synthesizing cells. The physiologic significance of the B cell differentiative activity of IL-2 remains to be investigated.
D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D007075:Immunoglobulin M / Q000096:biosynthesis*; D007376:Interleukin-2 / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D011971:Receptors, Immunologic / Q000378:metabolism; D015375:Receptors, Interleukin-2
D007075:Immunoglobulin M; D007376:Interleukin-2; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2