title: Proliferation of human B lymphocytes mediated by a soluble factor.
abstract: Recent studies have established the ability of a proportion of activated human B lymphocytes to undergo G1 phase cell cycle progression and subsequent S phase entry on exposure to factor(s) present in lectin-stimulated mononuclear cell-conditioned media. One factor capable of stimulating activated human B lymphocyte proliferation may be separated from peripheral blood lymphocyte-conditioned media by successive ammonium sulfate precipitation, ion exchange, and gel filtration chromatography. The isolated factor is distinct from the other well-described cytokines, possesses a molecular weight of 12,000-13,000, has a mildly acidic isoelectric point (at pH 6.3-6.6), is protease sensitive, and is relatively heat sensitive. The human B cell mitogenic factor possesses functional and cellular specificity in that its action is restricted to B lymphocytes and its function is proliferative. The production of the B cell mitogenic factor by T lymphocytes is augmented by the presence of a macrophage and further stimulated by syngeneic B cells.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D002453:Cell Cycle; D002457:Cell Extracts / Q000276:immunology*; D004355:Drug Stability; D006133:Growth Substances / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D015847:Interleukin-4; D037102:Lectins; D008213:Lymphocyte Activation; D008934:Mitogens; D014020:Tissue Extracts / Q000276:immunology*
chemical_list: D002457:Cell Extracts; D006133:Growth Substances; D037102:Lectins; D008934:Mitogens; D014020:Tissue Extracts; D015847:Interleukin-4