Study on the Mechanism of ‘ei’formation in the Bone Marrow Smears of the Patients with BMMNC-Coombs Test(+) Hematocytopenia

Objective To explore the mechanism of ‘erythroblastic island(EI)’ formation in the bone marrow of the patients with BMMNC-COOMBS( {)hematocytopenia.

Methods The category of BMMNC (hematopoietic stem cells, nucleated erythrocytes, granulocytes) -Ab in 48 patients with BMMNC-COOMBS( {) hematocytopenia were detected with FACS. The autologous antibody in the“EI” of these cases were explored with immuonhistofluorescence(IF). Clinical and other laboratory characteristics of these cases were also analyzed retrospectively.

Results Mouse anti-hIgG could be detected in the ‘EI’on the BM smear of 14 cases(29.17%), autologous antibody mainly deposited at the edge/membranes between macrophage and erythroblasts rather than in the cell plasma. Positive reaction were seen in all the cases with BMMNC-GlycoA IgG(+). The initial manifestation of the 14 patients was anemia. The percentage of reticulocyte (1.98%) and the serum level of IBIL of these cases (9.39 mmol/l)(5–24.90 mmol/l) were elevated in the 14 patients; Hypercellularity with higher percentage of erythroid (44.14%) in BM was seen in most patients. These cases had good reponse to high dosage of IVIgG (HDIVIG) or/and Glucocorticoids. There were significant difference of these indices between the IF(+), the IF(−)group and control group.

Conclusion Macrophage was connected with erythroblasts through autologous IgG in the‘EI’s of some patients with BMMNC-Coombs test(+) Hemocytopenia. These ‘EI’s were the places where macrophages devoured and destroyed erythroblasts rather than the places where erythroid development and differentiation. The pathogenic mechanism of this kind of disease might be associated with macrophages phagocyting and destroying more BM hematopoietic cells.