The Role Of Anti-beta2Glycoprotein â…  Antibodies In The Systemic Lupus Erythematosus Patient With Autoimmune Haemolytic Anaemia

Background:β2-glycoprotein I (β2GPI) is a plasma protein which consists of five complement-type repeats, i.e. Sushi-domains (Complement control protein, CCP). Putative phospholipid binding sites anchor in the fifth domain of the protein and pathological anti-β2-glycoprotein I antibodies are thought to bind to the first domain. Many experiments show that β2GPI bounds to the negatively charged structure of DNA, oxidized LDL, the apoptosis cells, syncytionboph-oblasts, endothelial cells, monocytes, and actived platelets. Anti-β2-GPI, which takes part in the progress of autoimmune hemolysis, has been found in a large number of patients with systemic lupus erythematous (SLE),5%-40%approximately. Some studies demonstrated higher positive results of anti-phospholipid antibody, such as aCL, among the patients with AIHA. While some experiments found that aCL shows higher efficiency, acting with target cells, with the assistant from β2GPI. However, few reports can be found, which describes the relationship between aβ2GPI and AIHA.Objective:To evaluate the correlation of anti-beta2glycoprotein I antibodies (β2GPI) with the patients who are stroked with systemic lupus erythematosus (SLE) accompanied with autoimmune hemolytic anemia (AIHA).Methods:According to the patients suffered with AIHA or not,104SLE patients were separated into the SLE-AIHA Group (22patients) and SLE-non-AIHA Group (82patients), excluding the patients with viral hepatitis, hypertension and diabetes. While20cases with AIHA were selected in the AIHA Group. All the cases were assessed with clinical and laboratory analyses. Levels of anti-β2GPI antibody, anticardiolipin antibody, anti-SM antibody, antinuclear antibody, anti-histone antibody, antiribosomal-P protein antibody and other autoantibodies were detected by Elisa assays.Results:The SLE-AIHA Group and SLE-non-AIHA Group had no significant difference between the frequency of anticardiolipin antibody, anti-SM antibody, antinuclear antibody, anti-histone antibody, antiribosomal-P protein antibody. However, the IgG isotype of anti-β2GPI antibody was with higher frequency in SLE-AIHA Group than that in the SLE-non-AIHA Group (P<0.05). There is no significant difference between SLE-AIHA group and AIHA group, for the frequency of anti-β2GPI antibody and anticardiolipin antibody. The higher incidence rate of renal impairment in was found patients with anti-β2GPI antibody, compared with patients without anti-β2GPI antibody (P<0.05). However, no correlation was found between anti-β2GPI levels and the severity of hemolysis, leucopenia, thrombocytopenia and other organs impairment. In the two groups of patients (SLE-AIHA and AIHA), the levels of IgG isotype anti-β2GPI associated with that of IgM isotype aCL (P<0.05). In SLE-AIHA group, the remission course of patients with anti-β2GPI was longer than those without anti-β2GPI.Conclusion:The higher prevalence of IgG isotype anti-β2GPI in SLE-AIHA patients and AIHA patients may suggest a synergistic immune activity of IgG isotype anti-β2GPI and aCL. Anti-β2GPI antibody may be one of a major factor which involves in the aggravation of renal function of patients with SLE, as well as the prognosis.