Inhibitory effects of the bone marrow microenvironment on erythroid progenitors in pure red cell aplasia

BACKGROUND: Primary pure red cell aplasia (PRCA) is a rare hematologic disorder characterized by severe anemia and selective erythroid hypoplasia in the bone marrow. While immune-mediated mechanisms are central to its pathogenesis, the role of soluble inflammatory factors in the bone marrow microenvironment remains poorly understood. METHODS: ) hematopoietic progenitor cells were obtained from untreated PRCA patients and healthy controls. K562 erythroleukemia cells were co-cultured with plasma and induced to undergo erythroid differentiation using hemin. Hemoglobin production was assessed by benzidine staining, and GATA1/GATA2 protein expression was analyzed by Western blotting. Erythroid colony-forming assays were performed to quantify small and large burst-forming unit-erythroid (BFU-E) and colony-forming unit-erythroid (CFU-E) colonies. Cytokine levels in bone marrow supernatant were measured. The effects of dexamethasone, cyclosporine A, and rapamycin on colony formation were also evaluated. RESULTS: cells from PRCA patients formed markedly fewer large BFU-E colonies than those from controls. Treatment with dexamethasone alone or in combination with cyclosporine A or rapamycin significantly restored large BFU-E colony formation. Cytokine analysis revealed significantly elevated levels of IL-6 and IL-10, with a trend toward increased IL-17A, in PRCA bone marrow plasma. CONCLUSIONS: Soluble factors in the PRCA bone marrow microenvironment may contribute to impaired erythroid progenitor function and hemoglobinization.