Factors in the tissue eosinophil responses in human immediate hypersensitivity reactions.

Factors underlying the eosinophil responses in the tissue sites of immediate hypersensitivity reactions have been investigated. A quantitative assessment of the number of eosinophils appearing in skin test reactions to ragweed antigen and compound 48/80 in ragweed-sensitive humans has been compared with several other parameters. There was a moderate, statistically significant, correlation with serum levels of IgE-class antiragweed antibody; also, eosinophil responses were minimal or absent in minimally positive threshold dilution skin tests. Tissue eosinophil responses were generally limited to those with baseline blood eosinophil levels of at least 150 mm3; however, there was no correlation between blood and tissue eosinophil levels in individual subjects. These findings suggest that the pathogenesis of the observed tissue eosinophil responses may be multifactorial.