The mediation of tissue eosinophilia in hypersensitivity reactions. V. Comparative study of tissue eosinophilia in the skin lesions of local and systemic passive cutaneous anaphylactic reactions.

Tissue eosinophilia in active cutaneous anaphylaxis reactions is biphasic: the early phase (6 hr) is induced by a low molecular (mol. wt. 300) factor (early ECF), and the delayed phase (24 hr) is mediated by synergy of two different factors (delayed ECF-a and -b). In this study, we report the mediation of tissue eosinophilia in passive cutaneous anaphylactic (PCA) reaction sites. Tissue eosinophilia in systemic PCA showed two phases with peaks at 6 hr and 24 hr, while that in local PCA was monophasic and peaked at 12 hr. A dialysable eosinophil chemotactic factor was isolated from the early stage (0-6 hr) of local PCA skin sites, and another chemotactic factor (mol. wt. 15,000), sharing a common antigenicity with guinea-pig serum C5, from 12-hr-old local PCA skin sites. On the other hand, a different chemotactic factor with a mol. wt. of about 70,000, sharing a common antigenicity with delayed ECF-b isolated from active cutaneous anaphylactic skin lesions, was isolated from 24-hr-old systemic PCA skin lesions. Although the dialysable factor was also isolated from systemic PCA skin sites, the factor from systemic PCA delayed skin sites may not contribute to delayed tissue eosinophilia, since the activity paralleled the intensity of basophil accumulation but not to that of eosinophils. It is thus suggested that tissue eosinophilia in systemic and local PCA reactions is mediated by different chemotactic factors.