The regulation of tissue eosinophil chemotactic factor and inhibitor in allergic skin lesions of Freund's complete adjuvant-treated guinea-pigs.

The regulation of tissue eosinophilia induced by dinitrophenyl-ascaris extract (DNP-As) was investigated in guinea-pigs. Biphasic tissue eosinophilia peaking at 6 and 24 hr was observed in the skin lesions in Bordetella pertussis vaccine (Bp)-treated animals. In contrast, only the early phase of tissue eosinophilia was observed in Freund's complete adjuvant (FCA)-treated animals. Although less eosinophil chemotactic activity was detected in 24-hr-old skin extract of FCA-treated animals (FCA-extract), evident activity was recovered in the concanavalin A eluate (Con A-eluate) when FCA-extract was fractionated by Con A Sepharose. The chemotactic factor in Con A-eluate of FCA-extract was confirmed to be the T cell-derived eosinophil chemotactic factor, termed Delayed ECF-a, which has been isolated from allergic skin lesions by immunoadsorption. Another factor from the same skin lesions, Delayed ECF-b (which is a serum-derived one), was not detected in the FCA-extract. When eosinophils were mixed or pretreated with Con A-effluent of FCA-extract, the treated cells failed to be attracted by Delayed ECF-a, while the response to Delayed ECF-b was not affected, indicating that the inhibition was selective for Delayed ECF-a but not for Delayed ECF-b, and the eosinophil chemotactic inhibitory factor (ECIF) acts on eosinophils directly. Major ECIF activity was associated with a mol. wt. of 70,000 and minor with 12,500. Furthermore, the activity was absorbed by eosinophils but not by macrophages suggesting that eosinophils have receptor sites for ECIF. It was thus suggested that the appearance of ECIF, which is selective for the response of eosinophils to Delayed ECF-a, and decreased Delayed ECF-b production resulted in the inhibition of delayed tissue eosinophilia in FCA-treated guinea-pigs.