Leukokinetic studies. XIV. Blood neutrophil kinetics in chronic, steady-state neutropenia.

The kinetics of blood neutrophils was investigated by means of the in vitro radioactive diisopropyl fluorophosphate method in 35 patients with a chronic, steady-state neutropenia. There were 17 patients in whom the half disappearance time of neutrophils was normal. In 10 of these patients, the production of neutrophils was low and in 7, production was normal. In 18 patients the half disappearance time of neutrophilic granulocytes was shorter than normal. The production of neutrophilic granulocytes was low in five of these patients, normal in eight patients, and increased in five. An attempt was made to correlate other laboratory measurements with the kinetic picture, but no relationship was found; the marrow neutrophil reserve as measured by endotoxin or cortisol injection; marrow cellularity on aspiration or biopsy; in vitro-labeling index with (3)HTdR; or serum lysozyme concentration proved of no value in identifying the various kinetic groups. The only finding that seemed to correlate with the kinetic picture was the presence or absence of splenomegaly. In 12 of the 18 patients with a short half disappearance time, splenomegaly was present whereas in 15 of 17 patients with a normal half disappearance time, there was no splenomegaly. Of 20 patients with greater than 1000 neutrophils per mm(3), 17 were found to have a normal total-blood neutrophil pool. Thus these patients, with many of their cells marginated, agree to have a "shift neutropenia."Myelocyte to blood transit time and myelocyte generation time, as measured in seven patients by in vivo labeling with diisopropy fluorophosphate, proved to be essentially normal. Thus, it appears that in chronic neutropenia, increased or decreased production of neutrophils is accomplished by increasing or decreasing early precursor input into the system.