Leukocytes and hypersensitivity reactions: I. Eosinophil response in skin window to ragweed extract, histamine, and compound 4880 in atopic and nonatopic individuals

Abstract

Eosinophil counts were made from coverslips obtained from skin windows after intradermal injections of buffered saline, histamine, compound 4880, and mixed ragweed extract in 17 atopic clinically sensitive, 7 skin reacting but clinically nonsensitive, and 11 nonatopic subjects. The concentration of challenging substance was selected on the basis of equal reactivity by titration and wheal size, but other concentrations were also tried. A challenging dose of a size individualized for the subject was necessary to produce the most effective response. When a potent reaginic serum and a proper dose of antigen are used, the eosinophil response in the passively sensitized site is not much different from that in the atopic individual. The response in the atopic, clinically nonsensitive persons appears to be less than the response in those with a history of pollinosis, although the number of subjects and their degree of sensitivity do not permit a final opinion. The eosinophil response to histamine and compound 4880 was found to be greater in atopic clinical than in atopic nonclinical or nonatopic subjects. The eosinophilia from these solutions is usually moderate, is absent at 45 minutes, begins at about 2 hours, is maximal at 6 hours, and is usually negligible at 24 hours. There is considerable variability and inconsistency in the cosinophil determination by this method, some of which is based on factors not yet recognized or corrected. However, it is concluded that conditions which constitute a minimal requirement are: accuracy of dose of challenging substance, a dose selected on basis of titration, repeated trials in the same subject, the counting of at least 1,000 leukocytes, and an averaging of representative areas on the same coverslip.