Circulating siderocytes in human subjects.

By Doms Kuirni, A. DEIss AND C. E. C wrwmcrr T HE OCCURRENCE of siderocytes in the blood of splenectomized patients, in the blood of some patients with hemolytic anemia, and particularly in splenectomized patients with persistent hemolytic anemia is well known.’5 More recently, as a result of experimental studies in swine,6” it has been recognized that the physiologic significance and metabolic behavior of siderotic granules contained within reticulocytes ( reticulated-siderocytes or R-S cells ) is quite different from such granules contained within non-reticulated, mature erythrocytes (S cells). Reticulated-siderocytes ( R-S cells) were observed in the circulation of iron replete animals during rapid blood regeneration induced by vigorous phlebotomy. The granules in such cells consisted of cytoplasmic aggregates of ferritin. The granules were metabolized by or removed from the cells during maturation in the circulation. The disappearance of the granules was independent of the spleen. Non-reticulated siderocytes (S cells) were observed in the circulation of animals with a defect in heme synthesis (pyridoxine-deficiency). The granules consisted of non-ferritin iron located within mitochondria. The removal of granules from these cells was dependent upon the spleen. In view of these differences between the two types of siderocytes in animals, it seemed appropriate to examine the occurrence of iron-containing granules in circulating erythrocytes of human subjects with reference to the type of siderocyte present. Such a study has not been performed heretofore in man. In this study the cells in the circulation of 80 normal subjects, 7 newborn infants, and 486 patients with a variety of hematologic disorders have been classified into those containing reticulum and no siderotic granules (R cells), those containing reticulum and siderotic granules (R-S cells), and those containing siderotic granules but no reticulum (S cells).