Cell Replication and Control

Abstract

Though all blood cells are derived from hematopoietic stem cells, the regulation of this production system is only partially understood. Negative feedback control mediated by erythropoietin and thrombopoietin regulates erythrocyte and platelet production, respectively, and colony stimulating factor regulates leukocyte levels. The local regulatory mechanisms within the hematopoietic stem cells are also not well characterized at this point. Due to their dynamic character, cyclical neutropenia and other periodic hematological disorders offer a rare opportunity to more fully understand the nature of these regulatory processes. We review here the salient clinical and laboratory features of a number of periodic hematological disorders, and show through a detailed example (cyclical neutropenia) how mathematical modeling can be used to quantify and test hypotheses about the origin of these interesting and unusual dynamics.