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Atherosclerosis and a high titre of antinuclear antibodies (ANA) are linked, concludes a recent study. Humoral immunity is implicated in inflammatory processes leading to atherosclerosis in mice, and autoantibodies to atheroma components have been shown in humans. This, however, is the first study of systemic autoimmunity and atherosclerosis in humans.
Grainger and Bethell screened for serum ANA—a marker of systemic autoimmunity—with an indirect immunofluorescent antibody test with HEp 2000 cells used in screening for autoimmune diseases. They compared 40 consecutive patients (aged 53–76) with advanced atherosclerosis (≥50 % blockage in three coronary arteries) confirmed by coronary angiography and 30 patients (48–74) with no plaques. Neither patients nor immediate (first degree) relatives had an autoimmune disease.
ANA were detected in nearly three quarters of patients with atherosclerosis but less than 20% without (within the range for their age). Overall, the odds of having ANA were significantly higher for coronary artery disease (11.67 (95% confidence interval 3.91 to 17.82; p<0.001)).
A speckled pattern characteristic of nucleolar staining occurred in three of five positive patients without atherosclerosis and 17 of 28 with; other patients showed staining of the centrosome or cytoplasm. Patients with atherosclerosis who had a previous myocardial infarction showed no difference in the proportion with ANA compared with those who had not.
The authors advocate a larger cohort study to permit pairwise matching for age and sex between the groups, but at face value ANA titre may be useful diagnostic marker for coronary artery disease. The tantalising question of the antibody's identity and whether it contributes to plaque development also remains.