Objectives: To explore the category, quantity and clinical significance of autoantibodies on bone marrow hematopoietic cells in patients with immunorelated cytopenia and evaluate the sensitivity of direct antiglobulin reaction (Coombs test ) of bone marrow mononuclear cells (BMMNC).
Methods: The category and the positive rate of autoantibodies on bone marrow hematopoietic stem cells, nucleated erythrocytes, granulocytes in 32 patients with uncertain immunorelated cytopenia were investigated by using BMMNC-Coombs test and double immunofluorescence flow cytometry.
Results: The positive rate of autoantibodies on bone marrow hematopoietic cells tested by flow cytometry was 90.63% which was higher than that by BMMNC-Coombs test (50.0%) (p < 0.05). In 29 positive cases, IgG autoantibody accounted for 6.90%, IgM13.8%, IgG+IgA 3.4%, IgG+IgM 31.0%, and IgG+IgM+IgA 44.8%. Of the 29 Patients, 25 (86.2%) with IgG autoantibody, 26 (89.7%) with IgM and 14 (48.3%) with IgA. The patients with IgG autoantibody alone had the lowest hemoglobin levels, and those with IgM autoantibody might have intravascular hemolytic findings. The response time of patients with IgG and IgG+IgM was shorter than that of the other patients. 91.3% of the patients had autoantibodies on bone marrow hematopoietic stem cells and showed pancytopenia, and 50% of the patients had autoantibodies on nucleated erythrocytes and granulocytes. Eleven of 13 patients with negative BMMNC-Coombs tests had autoantibodies on bone marrow hematopoietic stem cells detected by FACS. There was no significant difference of the quantities of the three categories of autoantibodies of nucleated erythrocytes and stem cells. The quantities of IgA on granulocytes were lower than that of IgG and IgM. There was no significant difference between IgG and IgM on granulocytes. The quantity of IgA on hematopoietic stem cells was significantly higher than that on nucleated erythrocytes or granulocytes.
Conclusions: The sensitivity of double immunofluorescence flow cytometry assay was higher than that of BMMNC-Coombs test for detecting autoantibodies. In immunorelated cytopenia patients, the predominant autoantibody was IgM which could cause intravascular hemolysis, and the second one was IgG which could cause severe anemia. Most immunorelated cytopenia patients had autoantibodies on hematopoietic stem cells and showed pancytopenia. IgA was more easily seen on the hematopoietic stem cells.