Cutaneous basophil hypersensitivity. II. A light and electron microscopic description.

Delayed onset erythematous skin reactions elicited in guinea pigs early in the course of sensitization with azobenzenearsonate-protein conjugates or with protein antigens in incomplete Freund's adjuvant or in saline were found to have a characteristic morphology which sets them apart from delayed hypersensitivity and the classic antibody mediated reactions. The principle feature was massive dermal infiltration with basophilic leukocytes. Mononuclear cells of several types including activated and small lymphocytes, monocytes, macrophages, and blast cells were also present.