Morphologic and functional heterogeneity of chronic neutropenia of childhood with normal neutrophil colony formation in vitro.

In order to obtain further knowledge of chronic neutropenia of childhood, we studied nine neutropenic infants six to ten months of age by in vitro techniques, including bone marrow culture, electron microscopy, and chemotaxis assay. Eight of the nine patients had a benign clinical course and the bone marrow aspirates showed a reduced number of segmented neutrophils. The ninth patient had a moderately severe course and the bone marrow showed maturation arrest at the promyelocyte stage. Bone marrow cultures demonstrated that the in vitro neutrophil colony formation and production of colony-stimulating activity were normal in all of the eight patients studied. Neutrophils from one of the nine patients had ultrastructural abnormalities such as decrease in number of primary and secondary granules and the presence of myelin figures in primary granules. Neutrophil chemotaxis was defective in three of the nine patients. All of the six patients in whom the neutrophil colony formation in agar, the ultrastructure of neutrophils, and neutrophil chemotaxis were normal recovered from the neutropenia between 11 and 30 months of age. These in vitro parameters appear to be useful for evaluating chronic neutropenia of childhood.