Anticardiolipin response and its association with infections in young and middle-aged patients with cerebral infarction.

Antibodies binding to solid-phase cardiolipin (anticardiolipin antibodies, ACA), which are closely associated with lupus anticoagulant activity, have been found in patients with thrombosis. ACA are often seen also in patients after acute infections. To study further our recent observation on the association between infection and cerebral infarction in young and middle-aged patients we measured anticardiolipin response (IgG, IgM, IgA) in paired sera from 54 consecutive patients with cerebral infarction under 50 years of age and in 54 community controls matched for sex and age. An elevated IgG-class ACA level or a significant change in level as observed in 2 serial samples occurred in 15 (28%) patients, but in only 4 (7%) controls (P less than 0.02). These ACA levels were only slightly elevated, and there were no patients with levels approaching values commonly seen in lupus anticoagulant-positive patients. Neither were there any patients with systemic lupus erythematosus (SLE) as an underlying disease. The combination of IgG-class ACA positivity and preceding probable bacterial infection (based on clinical, cultural or serologic data) was found in 10 patients (18%) but in only 2 controls (4%) (P less than 0.05). There were no significant differences in IgM- or IgA-class ACA between the patients and their controls. These results suggest that IgG-class ACA response associated with preceding probable bacterial infection is more common in patients with cerebral infarction than in their community controls. However, slightly elevated ACA are probably only indirect indicators of preceding infection and not directly involved in the pathogenesis of thrombosis itself.