Neutropenias of childhood

The recent advances in techniques for the study of neutrophil physiology permit a pathophysiologic classification of the neutropenias. As the methods for studying neutrophils are improved and become more widely available, it is hoped that an understanding of the neutropenias comparable to that of the anemias will be attained. Neutropenias due to decreased production, increased destruction, or a combination of these defects have been described. Increased knowledge of naturally occurring neutrophil antigens may make possible a more meaningful interpretation of cross-transfusion studies with labeled cells. Even now we can begin to separate the disorders of increased destruction into intracellular and extracellular mechanisms. Ineffective myelopoiesis is yet another example of neutrophil pathophysiology analogous to abnormal erythropoiesis. Some problems will be unique to the neutrophil such as the pseudoneutropenia due to an abnormal distribution of cells within the vascular compartments. The assignment of neutropenias within the physiologic classification offered may have to be changed as new information is obtained. The purpose of this report is to suggest that the pathophysiologic concept of the development of neutropenia serves as a schema by which the current and future neutropenic syndromes may be more meaningfully categorized and better understood. To this end a brief review of neutrophil physiology is offered.