Immune Complexes of Beta-2-Glicoprotein I Bounded to IgA: A Novel Marker Able to Predict Thrombosis After Renal Transplantation in Patients with Antiphospholipid Antibodies

Background —Antiphospholipid syndrome (APS) is characterized by recurrent thrombosis and/or gestational morbidity in patients with antiphospholipid autoantibodies (aPL). Predictive value of the presence of aPL is low and new markers are necessary to identify aPL carriers at higher risk and take preventive measures on them.The presence of circulating immune complexes of IgA bound to Beta2-glycoprotein-I (B2A-CIC) has been associated with occurrence of acute thrombotic events (TEV). In this work we study its possible predictive value for appearance of TEV in patients who are going to undergo transplant surgery, a well-known trigger of TEV in aPL carriers 94. Methods —We performed a follow-up study based on the Magnum 12+12 Cohort of patients who received a kidney transplant (N=1339). Three groups were established: Group-1 patients positive for IgA anti Beta2-glycoprotein-I (B2GP1) and B2A-CIC (N=125). Group-2 only positive for IgA anti B2GP1 (N=240). Control-group: negative for IgA anti B2GP1 (N=974). Levels of autoantibodies and B2A-CIC were quantified immediately before the transplant surgery and patients were followed-up for six months. Results —In group-1, 46.4% of patients suffer any type of thrombosis versus 10.4% in group-2 (p<0.001) and 8.6% in control-group (p<0.001). Incidence of graft thrombosis in group-1 (31.2%) was significantly higher than that observed in group-2 (3.3%, p<0.001) and control-group (2.6%, p<0.001). In a multivariate analysis, presence of B2A-CIC was an independent variable to suffer any type of post-transplant thrombosis (Hazard-ratio:6.72; 95% CI:4.81-9.37) and, prominently, for graft thrombosis (Hazard-ratio:14.75; 95% CI:9.11-23.89). No significant differences were found between B2A-CIC negative and control-group patients. Conclusions —Presence of B2A-CIC is a predictor of TEV. Patients positive for IgA anti-B2GP1 only are at risk of suffering thrombosis if they are B2A-CIC positive. If they are B2A-CIC negative patients, they have the same risk as the control-group. Treatments in order to prevent TEV should focus on B2A-CIC positive patients.