Chemotactic Responses of Normal Human Basophils to C5a and to Lymphocyte-Derived Chemotactic Factor

Peripheral blood basophils from normal human subjects responded chemotactically to the complement component C5a and also to the supernatant fluid from cultured human lymphocytes stimulated by mitogens or specific antigen. Basophil chemotactic factor (BCF) was detected in stimulated lymphocyte cultures within 24 hr and increased for the first 3 days. BCF was found after stimulation of lymphocytes by B or T cell mitogens as well as by specific antigen. The amount of BCF in culture fluids was independent of cell proliferation. Monocyte chemotactic factor (MCF) and BCF could not be separated from one another by Sephadex or DEAE chromatography. Both activities were eluted from Sephadex G-100 columns in a m. w. region of about 15,000 daltons and were found after ion exchange chromatography on DEAE in a peak eluted by 0.1 M NaCl. These findings suggest that mitogen or antigen-stimulated lymphocytes secrete a molecule that is chemotactic for both monocytes and basophils. Thus, in the absence of a basophil-specific chemotactic molecule, the preferential accumulation of basophils in certain types of delayed hypersensitivity skin reactions must be due to additional factors such as basophil chemotaxis augmentation factor.