The mediation of tissue eosinophilia in hypersensitivity reactions. IV. Production of delayed eosinophil chemotactic factor-a by peritoneal exudate cells from sensitized guinea-pigs in vitro.

An eosinophil chemotactic factor (ECF) was produced in the cell-free culture supernatants (CFS) of peritoneal exudate cells (PEC) from guinea-pigs immunized with dinitrophenyl derivatives of ascaris extract (DNP-As), when stimulated by the antigen in vitro without activation by immune complexes. A 2 or 6 hr pulse of the antigen was sufficient for ECF production, whereas long time incubation (48 hr) was required for the production of a sufficient amount of the factor. Treatment of PEC by cycloheximide resulted in the reduction of ECF production, suggesting that protein synthesis is essential. Its generation appeared carrier-specific and the source of the factor is presumed to be lymphocytes, probably T lymphocyte. The factor with a molecular weight of 70,000 shared a common antigenicity with delayed eosinophil chemotactic factor-a (delayed ECF-a), which was isolated from the skin lesions showing delayed tissue eosinophilia in vivo.