Specificity of anti-phospholipid antibodies in infectious mononucleosis: arole for anti-cofactor protein antibodies

The antigen specificity of anti-phospholipid antibodies in infectious monon ucleosis (IM) was studied using ELISA for the detection of anti-beta(2)-gly coprotein I (beta(2)-GPI), anti-annexin V, anti-protein S and anti-prothrom bin antibodies and TLC immunostaining for the detection of anti-phospholipi d antibodies. This technique enabled us to look at antibodies reacting to ' pure' phospholipid antigens in the absence of protein contamination. Sera f rom 46 patients with IM, 18 with systemic lupus erythematosus (SLE), 21 wit h primary anti-phospholipid antibody syndrome (PAPS), 50 with Helicobacter pylori infection and 30 healthy blood donors were tested. This study highli ghts anti-phospholipid antibodies in patients with IM as specific 'pure' an ti-cardiolipin antibodies, while in PAPS and SLE patients anti-phosphatidyl serine and anti-phosphatidylethanolamine antibodies were also found. This i nvestigation also shows that the anti-cardiolipin antibodies found in IM ca n be present with anti-cofactor protein antibodies. The higher prevalence o f anti-cofactor antibodies found in IM sera than in Helicobacter pylori ser a may be due to the immunostimulatory effect and/or the polyclonal activati on often observed in course of Epstein-Barr virus infection. However, anti- beta(2)-GPI and, to a lesser extent, anti-prothrombin antibodies occur with a significantly lower prevalence in IM than in PAPS patients. This finding suggests that these antibodies should be regarded as the expression of the broad autoimmune syndrome involving the phospholipid-binding plasma protei ns.