The effect of eosinophil chemotactic factors on in vitro eosinopoiesis in the guinea pig.

The influx of eosinophils to tissue sites is regulated by several well-characterized eosinophil chemotactic factors. In the present investigation the effect of such factors on eosinopoiesis was studied in guinea pig liquid bone marrow cultures. Addition of neutrophil-derived eosinophil chemotactic leukotrienes, synthetic leukotriene B4, zymosan-activated serum, purified hog C3a, C5a, C5a-des-arg, and synthetic N-formyl-methionyl-phenylalanine did not increase eosinophil numbers in marrow cultures, while supernatants of spleen or lymph node cells stimulated by concanavalin A were highly effective. 3H-thymidine labelling of cultured eosinophils was not increased by any of the added mediators. A quantitative correlation between eosinopoietic and eosinotactic activity could not be established. These in vitro data suggest therefore that eosinopoiesis and migration of guinea pig eosinophils to tissue sites are regulated by separate chemical mediators.