Red-cell hypoplasia and increased bone marrow reticulin in systemic lupus erythematosus: reversal with corticosteroid therapy.

A 29-year-old Chinese male developed severe aregenerative anemia. The bone marrow was diffusely hypercellular with increased marrow reticulin and a persistent failure of erythroid differentiation beyond the pronormoblast stage. Although he did not manifest classic features of systemic lupus erythematosus, multiple serologic studies were in accord with this diagnosis. The patient's defect in erythropoiesis was studied by an in vitro technique for the growth of erythroid colonies. Despite the severe erythroid hypoplasia, the patient's marrow yielded abundant large erythroid colonies. Serum erythropoietin activity was high as judged by use of this in vitro assay. Although the patient's native serum did not affect colony formation, a separated IgG fraction was markedly inhibitory to colony growth. This suggests that the erythroid hypoplasia may have resulted from a unique autoantibody. The patient's hematologic abnormalities completely reversed following treatment with corticosteroids.