The mediation of tissue eosinophilia in hypersensitivity reactions. III. Separation of two different delayed eosinophil chemotactic factors and transfer of these factors by serum or cells from sensitized guinea-pigs.

Two different eosinophil chemotactic factors (delayed ECF-a and ECF-b) were isolated from the delayed phase (24 hr old) of eosinophil-rich inflammatory reaction sites induced by DNP-ascaris extract, which could be separated by DEAE-Sephadex. Both the factors were thermolabile (56 degrees, 30 min) and had a mol. wt of about 70,000, whereas they were clearly different in antigenicity. Delayed tissue eosinophilia was shown to be mediated by peritoneal exudate cells (PEC) and serum from immunized donors to recipients. A chemotactic factor, closely resembling a delayed ECF-a, was isolated from the skin lesions of recipients transferred by sensitized PEC and challenged. Another factor, closely resembling a delayed ECF-b, was isolated from those of recipients transferred by immune serum and challenged. Furthermore, we have shown that delayed ECF-b, but not delayed ECF-a, shared a common antigenicity with some guinea-pig serum component. Thus we concluded that delayed tissue eosinophilia was mediated by the combined actions of two different factors, delayed ECF-a and ECF-b.