Chronic Childhood Neutropenia: Studies on the in vitro Clonogenicity of Bone Marrow Myeloid Progenitors

Abstract

Bone marrow mononuclear cells (MNC) from 6 pediatric patients with chronic neutropenia were tested for myeloid colony formation upon stimulation with the supernatant of the 5637 cell line or with recom-binant granulocyte-macrophage colony-stimulating factor or interleukin 3. Heterogeneous patterns of response of myeloid progenitors were observed in the individual patients, with no colony growth in 2 cases and abnormalities of colony formation or composition in two additional cases. Morphologic and surface marker analyses showed that the bone marrow of some patients contained an excess of lymphocytes with an altered subset distribution. In order to investigate whether or not there was a relationship between the latter abnormality and the observed clonogenic defects, marrow MNC were tested for myeloid colony formation before and after lymphocyte depletion. No evidence for a cell-mediated suppression of colony growth was obtained; likewise, patient sera failed to inhibit colony formation by normal bone marrow myeloid progenitors. Taken together, these data make it unlikely that, in our cases, immunologic mechanisms were responsible for the pathogenesis of chronic neutropenia.