Anti-heat shock protein (hsp)72 antibodies are present in patients with Graves' disease (GD) and in smoking control subjects

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Abstract
SUMMARY: Hsp72 is expressed in thyroidal tissue and on retroocular fibroblasts from patients with GD. In this study we investigated whether GD patients have hsp72 antibodies, and if they correlate with disease characteristics. Because smoking is associated with GD and might up-regulate hsp72 expression, we also studied the effect of smoking on hsp antibody levels. Hsp72 IgG antibodies were determined by dot-blotting, using recombinant human stress-inducible hsp72. Dot-blot densities were measured using a videoimaging system in 38 healthy controls, 45 patients with GD, including 34 with varying degrees of ophthalmopathy, and in 13 GD patients before and after treatment of thyrotoxicosis with methimazole. Hsp72 antibodies were detectable more frequently in GD patients (26/45, 58%), than in controls (12/38, 32% P<0·02). GD patients had higher antibody levels than controls; mean ± s.e.m. optical densities: 26·8 ± 2·6 versus 18·8 ± 2·4 (P = 0·018). Levels did not correlate with any parameter of disease severity or activity. Hsp72 antibody levels did not change upon reaching euthiyroidism. In controls, but not in patients, hsp72 antibodies could be detected more frequently in smokers (6/10, 60%) versus non-smokers (6/28, 21%; P = 0·024). Patients with GD have higher hsp72 IgG antibody levels than controls, without correlation with any disease characteristic. Among healthy controls, smoking is associated with elevated hsp72 antibodies. This suggests that these antibodies might be a marker for autoimmune susceptibility.