Tissue eosinophilia in human coccidioidomycosis.

Eosinophilia in peripheral blood and tissue of patients with coccidioidomyocsis was reviewed in an examination of the importance of this cellular response to Coccidioides immitis. Peripheral blood eosinophilia (greater than 5%) was found in each of two patients with primary infection but was markedly more pronounced (27%-53%) in three of five patients with disseminated coccidioidomycosis. Unusually large numbers of tissue eosinophils and organized microabscesses containing eosinophils were found in six patients with progressive or disseminated disease. These six patients all demonstrated cutaneous anergy to coccidioidin. Eosinophilic microabscesses were found surrounding rupturing spherules and free endospores. Phagocytosis of free endospores was not demonstrated by the technique used. The bone marrow of two patients with disseminated disease showed a marked increase in eosinophilic myeloid precursors; this result suggested the presence of an eosinophilopoietin. Although peripheral blood eosinophilia has been explained as a hypersensitivity response to C. immitis that represents a favorable prognosis, the data reported herein suggest that peripheral blood eosinophilia of greater than 20% and the presence of eosinophilic microabscesses correlate with progressive or disseminated infection and thus are indicative of a poor prognosis.