Neutrophil marrow in chronic benign idiopathic neutropenia.

Quantitative studies of neutrophil marrow were carried out in 10 patients with chronic neutropenia (60 to 1,970 cells/microliter) with no other abnormalities and no serious infections. Neutrophil marrow cellularity was determined from neutrophil-normoblast ratios in marrow sections and ferrokinetic estimation of normoblasts. The results were interpreted in the light of 95 per cent confidence limits previously observed in 13 normal volunteer subjects. Three distinct neutrophil marrow profiles were determined by the numbers of promyelocytes and myelocytes and of segmented marrow cells. Tentative kinetic interpretation was based on the expectation that the physiologic marrow response to removal of neutrophils from circulation would produce an increase in promyelocytes and myelocytes due to influx and proliferation, and a decrease in marrow segmented cells due to accelerated release. In two patients increased segmented marrow cells were consistent with an abnormality of release. Decreased numbers of promyelocytes and myelocytes in three patients was consistent with decreased proliferation. In five patients basal numbers of promyelocytes and myelocytes suggested abnormal proliferation or abnormal regulation of myelopoiesis. The number of metamyelocytes and band forms relative to promyelocytes and myelocytes was normal in all 10 patients: none had evidence of cell loss during postmitotic maturation. The term "chronic benign idiopathic neutropenia" appears to embrace more than one mechanism for neutropenia. All 10 patients had evidence of abnormal neutrophil marrow function.