Total absence of eosinophils in a patient with an allergic disorder.

A 45-year-old woman with a 25-year history of episodic urticaria and rhinitis had no detectable eosinophils in blood or bone marrow; levels of other leukocytes were normal. No eosinophils were found in the nasal discharge or the exudate elicited in skin windows by ragweed extract, to which the patient exhibited an immediate-type hypersensitivity response. A complement-dependent IgG-related activity in the patient's serum cytotoxically degranulated human eosinophils in vitro without affecting neutrophils. Antieosinophil activity was confirmed by the ability of a single dose of the patient's serum to suppress significantly the eosinophil counts in monkeys for up to 12 hours. This is the first description of an isolated absence of eosinophils, a condition that may present with allergic manifestations.