A BASOPHIL-ACTIVATING FACTOR FROM HUMAN LYMPHOCYTES-T

Abstract

Human T lymphocytes stimulated with phytohemagglutinin (PHA) or streptokinase-streptodomase (Sk-SD) generate an activity which elicits noncytotoxic histamine release from human basophils. Filtration of the T lymphocyte-derived activity on columns of Sephadex G-100 and Fractogel 55F sequentially revealed 1 predominant basophil-activating factor of MW 70,000-90,000, that was designated BAF-T. BAF-T was composed of 2 acidic proteins of Pi [isoelectric point] 4.4 and 5.2-5.5, as assessed by isoelectric focusing. The distinction of BAF-T from IgE was confirmed by the failure of BAF-T to bind to an anti-IgE affinity column and the capacity of BAF-T to release histamine maximally from basophils desensitized to IgE-dependent stimuli. The inability of BAF-T to release histamine from human lung mast cells and dog cutaneous mastocytoma cells suggests target cell specificity. The source and activity of BAF-T are consistent with a specific contribution of this mediator to human cellular immune and hypersensitivity response involving T lymphocytes and basophils.