Association of beta(2)-glycoprotein I IgG and IgM antibodies with thrombosis and thrombocytopenia

Antiphospholipid antibodies (APA) have been known for decades. Their relati on to clinical manifestations, primarily thromboses and thrombocytopenia, w as recognised in the 1980s. In this clinical study two cohorts of patients, a population-based (84 patients with systemic lupus erythematosus (SLE)) a nd a hospital-based (87 patients with SLE and 53 with other connective tiss ue diseases) were investigated for APA and associated clinical manifestatio ns. Anticardiolipin antibodies (ACA) of IgG and IgM classes were found in 1 3 and 38% of the population-based patients and in 29 and 58% of the hospita l-based patients, respectively. The corresponding figures for antibodies ag ainst beta (2)-glycoprotein I (anti-beta (2)GPI) were 15 and 10% in the pop ulation-based patients and 14 and 8% in the hospital-based cohort. Anti-bet a (2)GPI antibodies were always found in association with the corresponding immunoglobulin class of ACA. In both cohorts anti-beta (2)GPI of the IgG class were associated with arte rial/venous occlusion, a result concordant with other studies. A novel find ing in both cohorts, however, was an association between thrombocytopenia a nd IgM anti-beta (2)GPI.