Granulopoiesis in Neutropenic Disorders

Evaluation of proliferative activity of granulocytic progenitor cells from marrows of neutropenic patients was performed by utilizing in vitro culture methods measuring granulocytic colony-forming capacity (CFC) and the proportion of granulocytic progenitor cells in the DNA synthetic (S) phase of the cell cycle. Except for low CFC values found in five patients with myeloid hypoplasia, the remaining 20 patients had values comparable to or above those of 22 control subjects. In five control subjects 31%-39% of the progenitors were in S phase. The proportion of such cells from marrow of a patient with cyclic neutropenia markedly increased as his peripheral neutrophils decreased from peak to lowest levels. In patients with splenomegaly or megaloblastic anemia, where rapid granulocyte turnover was expected, the proportion of progenitors in S phase was increased. In contrast, in patients with idiopathic neutropenia and Felty’s syndrome this proportion was normal or decreased, suggesting that suboptimal granulopoietic compensation contributed to the neutropenia present in these disorders.