Study of IgG Subclass of the Patients with Immuno-Related Hemocytopenia

Objective: To investigate the immunoglobulin G (IgG)sublass on the membrane of bone marrow(BM) hematopoietic cells and IgG levels in BM supernatant of patients with immuno-related hemtocytopenia(IRH).

Method: Newly diagnosed IRH patients and ICUS patients were enrolled in this study, as well as healthy donors as controls. The categories of auto-antibodies(IgM and IgG) on the membrane of BM hemmatopoietic cells(CD15+,CD34+ and GlyCoA+ cells)were assayed by Flow cytometry(FCM). The categories of auto-antibodies(IgG1 and IgG3) on the membrane of BM hemmatopoietic cells were assayed by FCM.BM nucleated cells antibodies (IgG1AIgG2AIgG3 and IgG4)were detected by immunohistochemical staining. The IgG1AIgG2AIgG3 and IgG4 levels in BM supernatant were detected by Cytometric Bead Array (CBA)GThe ratio of CD5+CD19+/CD19+ in blood were tested by FCMGThe mRNA expression of IgG1 in peripheral blood were detected by RT-PCR.

Result: The positive rate of antibodies (IgG) on BM hemmatopoietic cells of IRH patients was 58.69(27/46), which was significantly higher than that in ICUS group(0%) and healthy control group(0%). The positive rate of IgG1 on CD15+ cells was (3.13±1.80)% in IRH group, which was significantly higher than that in healthy control group. The positive rate of IgG3 on CD15+ cells was(2.73±2.09)% in IRH group, which was significantly higher than that in healthy control group. The positive rate of IgG1 on GlyCoA+ cells was( 3.97±2.21)% in IRH group,which was significantly higher than that in healthy control group. The positive rate of IgG3 on GlyCoA+ cells was (2.24±1.82)% in IRH group,which was significantly higher than that in healthy control group. IgG subclass(IgG1AIgG2AIgG3 and IgG4)on BM nucleated cells were detected by Immunohistochemistry. 11/15 IRH patients' IgG1 positive cells≥3(count 100 bone marrow nucleated cells). There were rarely IgG1+ cells in ICUS patients and healthy donors' bone marrow smears. IgG2,IgG3 and IgG4 positive BM nucleated cells were rarely detected in three groups by immunohistochemistry. The IgG1 level in IRH group was (6998±2498)mg/L which was higher than remission group (4702±1235)mg/L, healthy control group (5613±1640) mg/L and ICUS group (5166±1761) mg/L, P<0.05. The IgG3 level in IRH group was (637±252)mg/Lwhich was higher than remission group(415±196)mg/L,healthy control group (422±212) mg/L and

ICUS group (485±197) mg/L, P<0.05. IgG2 levels in four groups were no statistical difference. IgG4 levels in these four groups were no statistical difference. The total IgG level in IRH group was (10903±2576)mg/L which was higher than remission group(8468±1957)mg/L, P<0.05. The ratio of CD5+CD19+/CD19+ in IRH group was(23.34±9.36)% which were significance higher than healthy control group(13.67±5.10)% and ICUS group(12.40±3.63)% (P<0.01). IgG1 level had a positive correlation with the proportion of CD5+ B lymphocytes(r=0.392, P =0.043). There was an inverse correlation between the IgG1 level and the count of neutrophil (r = -0.459, P = 0.016) in IRH patients. There was an inverse correlation between the level of IgG3 and hemoglobin(Hb) (r = -0.389, P = 0.045) in IRH patients. In IRH group, the mRNA expression of IgG1 in peripheral blood is 5.27±4.83 which is higher than healthy control 1.58±1.50, P<0.05.

Conclusion: There are auto-antibodies IgG on the membrane of BM hematopoietic cells of IRH patients. IgG1 and IgG3 on BM nucleated cells increased significantly in BMMNC-Ab IgG positive IRH patients.