Acquisition of Autophagic Vacuoles by Human Erythrocytes Physiological Role of the Spleen

Using interference-contrast microscopy, erythrocyte vacuoles can be rapidly and easily distinguished. Because of the shadowing effect inherent in this optical system they appear as surface indentations. Twenty splenectomized patients with both normal and abnormal erythropoiesis had 54.3 per cent vacuolated cells as compared to 2.1 per cent in a control group of normal adults. A splenectomized patient with pure red cell aplasia, whose erythrocyte mass was maintained with fresh normal blood, had 44 per cent vacuolated cells. Electron microscopy thin sections showed numerous erythrocyte inclusions and vacuoles which were morphologically suggestive of hemoglobin degeneration. Similar inclusions were noted in all splenectomized subjects studied, and were found in greater numbers in patients with young cell populations. They were rare in normals with intact spleens. Transfusion studies show that these inclusions can be acquired by normal mature erythrocytes when circulating in an asplenic patient. Further, they are cleared from the circulation in the presence of an intact spleen without measurable loss of red cell viability. The evidence suggests that, in the absence of a spleen, autophagic vacuoles may occur in situ in all circulating red cells. It is presumed that these inclusions would normally be removed as a physiological process by a functioning spleen.