Detection of erythroblast antibodies in mitogen-stimulated bone marrow cultures from patients with myelodysplastic syndromes

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Abstract

BACKGROUND:

Low-risk myelodysplastic syndromes (MDS) show several immunologic abnormalities, including increased frequency of autoimmune manifestations and/or overt autoimmune diseases, whose prognostic significance still remains controversial.

STUDY DESIGN AND METHODS:

We studied the presence of erythroblast antibodies in mitogen-stimulated bone marrow (BM) cultures of 70 patients with early-stage MDS (refractory anemia and refractory anemia with ringed sideroblasts).

RESULTS:

Sixty-six percent of patients showed positive erythroblast antibodies, along with BM erythroid hyperplasia and a hemolytic picture in the peripheral blood. Supernatants from positive cultures induced an increase of overall cellularity, the appearance of erythroblastic clustering, and dyserythropoietic signs in normal BM. We identified CD45dimGly-AdimCD71bright cells (red blood cell precursors at different maturation stage) as the target of the antibodies. Erythropoietin (EPO) levels were reduced and EPO receptors (EPO-R) increased in BM culture supernatants from positive patients. However, flow cytometric analysis showed that neither EPO nor EPO-R was involved in an abnormal stimulation driven by these autoantibodies. Values of the proapoptotic protein Bax were increased in positive patients and Bcl-2 levels were decreased, although not significantly.

CONCLUSION:

MDS patients with anti-erythroblast autoimmunity showed increased BM apoptosis, suggesting that the autoimmune reaction may contribute to an unfavorable BM microenvironment for optimal erythropoiesis.

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