[Anticardiolipin antibodies and Horton disease].

A prospective study, including 86 patients with giant cell arteritis proven by temporal artery biopsies, was performed to determine the prevalence of anticardiolipin antibodies, the antibody isotype, the relationship of antibodies to ischemic involvement and their evolution during corticosteroid treatment. Controls were obtained from 50 subjects without vasculitis or autoimmune disorders. Before treatment, 50% of patients' sera contained anti-cardiolipin antibodies (vs 8% in controls, p < 0.0001). These antibodies were IgG-ACL in 36% of patients and IgM-ACL in 17% of patients (vs respectively, 4% and 2% in controls). No significant association was observed between the incidence of ischemic ocular complications and the levels of anti-cardiolipin antibodies. During corticosteroid treatment, the level of anti-cardiolipin antibodies, mostly IgG class, decreased to become negative in 2 months. An increase of these antibodies was observed with the occurrence of relapses in four patients, after the end of corticosteroid therapy. The significance of IgG and IgM antibodies is different in giant cell arteritis. IgG antibodies may be markers of the course of this vasculitis.