The Maturation Rate of Reticulocytes

An in vitro culture technic for the study of reticulocyte maturation was described. The method gave reproducible results and proved to be of value in the comparative study of reticulocyte maturation in blood disorders. By this method it was shown that variations in the reticulocyte maturation in vitro paralleled similar variations present in vivo.

The maturation of reticulocytes from patients with different types of anemia was investigated. In some anemias the in vitro maturation of reticulocytes was prolonged, not only because younger reticulocytes were present in the blood, but also because the rate at which the reticulum substance disappeared was delayed. This was particularly evident in the anemia of chronic uremia, in Cooley’s anemia and in pernicious anemia in relapse. In only occasional cases of hereditary spherocytosis and of autoimmune hemolytic anemia was the rate of reticulocyte maturation found to be moderately delayed. In patients with iron deficiency anemia or bleeding anemia it was always normal.

From the above findings the following conclusions were derived:

1. The reticulocyte number in the circulating blood is the resultant of three variables: (a) the rate of output of new reticulocytes from the bone marrow; (b) the stage of maturation at which reticulocytes are delivered into the peripheral circulation; (c) the rate of disappearance of the reticulum substance.

2. The number of reticulocytes in the circulating blood cannot be indiscriminately used as a precise index of red cell production in erythrokinetics.

3. There is good reason to believe that a defect in the rate at which the reticulocytes mature in the circulating blood is an index of a similar defect in the process of erythroblastic differentiation in the bone marrow.