ERYTHROID COLONY FORMATION INVITRO FROM MARROW OF DOGS WITH CYCLIC HEMATOPOIESIS - INTERRELATIONSHIP OF PROGENITOR CELLS

Abstract

Committed erythroid progenitor cells (Colony Forming Units-Erythroid, CFU-E) were studied in canine cyclic hematopoiesis (CH) utilizing a semi-solid methyl cellulose culture system. Erythroid colonies were stimulated by adding a standard volume of serum from normal dogs that were phlebotomized and subjected to hypoxia. CFU-E fluctuated over the cycle in dogs with CH from concentrations 4-5 times normal during the periods of peripheral blood neutropenia to less than 1/10 of normal during the phases of elevated peripheral blood neutrophil counts. In spite of these marked fluctuations there was no change in the proliferation rate of the CFU-E as estimated by the tritiated thymidine (3H-TdR) suicide technique. Failure to demonstrate a change in the CFU-E proliferation rate may have been related to the relative maturity of these cells with the fluctuations in number resulting from a feed-in from more immature cells. CFU-E fluctuated in the same phase as committed granulocytic progenitor cells (CFU-C). Current knowledge of the interrelationships of marrow progenitor cells and events in the peripheral blood of dogs with CH was briefly reviewed and some additional questions, raised by recent studies regarding the pathogenesis of this disease, were discussed.