Granulopoietic differentiation in long‐term bone marrow cultures from children with congenital neutropenia

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Abstract
The capacity of granulopoietic precursor cells (CFU‐GM) to differentiate in vitro was evaluated in five children with congenital neutropenia using short‐term colony assays and long‐term marrow cultures. In all five children, methylcellulose assays revealed normal numbers of CFU‐GM, which displayed an appropriate response to various sources of GM‐CSF and differentiated up to the polymorphonuclear leukocyte state (PMN). In contrast, neutrophil PMN were not observed in long‐term bone marrow cultures from three patients, despite a normal production of CFU‐GM, myeloblasts, and promyelocytes during the 5‐6‐week culture period. Thus, in these patients, the characteristic “block” in granulocytic maturation observed in vivo was reproduced in vitro in long‐term cultures. Granulocytic differentiation proceeded normally in long‐term cultures from the two other patients, thus indicating heterogeneity in the expression of the defect. These results might indicate abnormal interactions between stromal and hematopoietic cells in long‐term marrow cultures from some patients with congenital neutropenia. Furthermore, our results showed some correlation between the granulocytic defect in vitro and the clinical outcome in vivo.