Chronic schistosomiasis mansoni: splenic myelopoiesis and inhibition of neutrophil granulocytopoiesis mediated by the sera of patients.

The correlation among schistosomal infection, splenomegaly, and modifications of circulating blood leukocytes was studied. Peripheral neutropenia was found to occur concomitantly with incomplete splenic myelopoiesis of the neutrophil line. Sera from patients with schistosomiasis modified the proliferation of murine bone-marrow cells in soft-agar cultures. A total inhibition of neutrophil differentiation was compensated for by a proportional increase in macrophage differentiation. The neutrophil-inhibitory activity of sera of patients with schistosomiasis may be responsible for the delayed in vivo maturation of neutrophils in the bone marrow and spleen of these patients.