Recovery of Blood Neutrophils After Acute Peripheral Depletion

¹ From the Division of Biological and Medical Research, Argonne National Laboratory, Lemont, Illinois

Blood neutrophil recovery in the dog appears to be qualitatively similar whether leucopenia is achieved by injection of leucocyte antiserum to remove the cells in vivo or by exchange transfusion with leucocyte-depleted blood. Return to the control level after antiserum injection occurs within 3–5 hours with neutropenias in excess of about 50% and is followed by neutrophilia of variable degree with restoration of the normal count usually by 24 hours. There is reason to think that recovery is accomplished in large part by an accelerated release of cells from marrow. This conclusion, which is based mainly upon the appearance of numerous band cells in the periphery, is supported by the results obtained in x-irradiated animals and is consistent with related observations by others and with theoretical considerations of neutrophil balance. The extent of release of nonsegmented cells is related more to the relative (percentage) change than to the absolute decrease in neutrophils. These observations can be interpreted to mean that the number of mature cells available for release from the marrow reservoir is a function of the normal steady state level in blood. Possible mechanisms of compensation for the decline in cells in the periphery are discussed and exploratory studies are reported. It is suggested that the control system may include a suppressor feedback between mature neutrophils and blood-forming sites.