Ineffective erythropoiesis in the spleen of a patient with pyruvate kinase deficiency.

In this study, possible adverse effects of pyruvate kinase (PK) deficiency on the maturation of erythroid progenitors were investigated. A 4-year-old Japanese girl with severe PK deficiency underwent splenectomy to reduce her need for blood transfusions. The spleen was examined a histologically, and the hematopoietic progenitors in the spleen were assayed to evaluate the extramedullary hematopoiesis of this PK-deficient subject. The number of hematopoietic progenitors including CFU-GM, BFU-E and CFU-GEMM in the spleen of the PK-deficient patient was much higher than those found in control spleens, indicating enhanced extramedullary hematopoiesis. TUNEL assay demonstrated apoptotic cells in the splenic red pulp of the PK-deficient patient. The expression of 7A6 antigen was detected in cells isolated from spleen and in cells cultured in vitro, but only in those cells that were positive for glycophorin A. These results provide evidence that the metabolic disturbances in PK deficiency affect not only the survival of red cells but also the maturation of erythroid progenitors, which results in premature cell death, i.e., apoptosis.