期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：19
页码：5998-6002
DOI：10.1073/pnas.79.19.5998
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Recent studies have established the ability of human B lymphocytes to undergo G1-phase cell cycle progression and subsequent DNA synthesis upon exposure to factor(s) present in media conditioned by lectin-stimulated mononuclear cells. Procedures for the isolation of such a cytokine have been the focus of the present investigation. Conditioned medium from cells stimulated by lectin for 72 hr was fractionated by ammonium sulfate precipitation, ion-exchange chromatography, and gel filtration chromatography. During the isolation procedure the proliferation-stimulating activity of the column fractions was assayed concurrently on purified human T cells, purified human B cells, and murine thymocytes. T cell and B cell stimulatory factors present in the initial conditioned medium were found to copurify during ammonium sulfate precipitation, DEAE-Sephadex chromatography, and Bio-Gel P-30 gel filtration. However, partial separation of these two activities was achieved after Bio-Gel P-100 gel filtration. Analytic polyacrylamide gel electrophoresis of radiolabeled Bio-Gel P-100 column fractions demonstrated a distinct protein band of 14,000-15,000 daltons in those column fractions predominantly supporting T cell growth and a distinct protein band of 12,000-13,000 daltons for those fractions predominantly supporting B cell growth. The fractions associated with B cell mitogenic activity induced B cell S-phase entry in a proportion of B lymphocytes in the absence of any detectable IgM secretion.
