Pure red blood cell aplasia associated with paraproteinemia: in vitro studies of erythropoiesis.

Pure red cell aplasia (PRCA) and monoclonal gammopathy were detected simultaneously in a 57 year old man with severe anemia. While erythroid burst forming units (BFU-E) were absent from blood, his bone marrow contained a high normal number of BFU-E in the absence of morphologically recognizable erythroid precursors. Serum from the patient did not inhibit the growth of BFU-E from normal blood suggesting that his PRCA was not antibody mediated. These studies suggest that in the patient the inability to produce erythrocytes was due to a block in the maturation of BFU-E; however, they do not indicate an etiology for this block. The absence of blood BFU-E and their abundance in the marrow may result from selective trapping of these cells by the marrow-blood barrier.