[Detection of erythropoietic inhibitor factor in a case of acute non-lymphocytic leukemia after allogenic bone marrow transplantation].

: A 36-year-old man was diagnosed as having acute non-lymphocytic leukemia (AML M5b) in 1985 and received allogenic bone marrow transplantation from an ABO-mismatched sibling in January 1987. Recovery of erythropoiesis in this patient was delayed, then the hemoglobin level improved in parallel with disappearance of anti-A antibody in the serum on day 260 post transplantation. However, as anemia occurred again despite no relapse of leukemia on day 350, we tried to determine the presence of erythropoietic inhibitory factor in this patients. Erythroid colony formation was decreased when bone marrow cells were co-cultured with peripheral mononuclear cells from the patient. Further, erythroid colony inhibitory activity was found in conditioned medium of PHA-stimulated T cells from the patient. Sephadex gel fractionation showed that the molecular weight of this inhibitory factor was approximately 11,000 and addition of a high concentration of EPO did not eliminate the inhibitory activity. These findings suggest that the novel inhibitor described in this manuscript, produced by T cells, was differed from previously reported inhibitors such as anti-EPO antibody, spermine and uremic toxins.