Specific IgE positivity against inhalant allergens and development of autoimmune disease.

BACKGROUND

Allergic and autoimmune diseases have been suggested to be inversely associated. We investigated the association between atopy and development of any and specific types of autoimmune disease.

METHODS

We included a total of 14,849 individuals from five population-based studies with measurements of atopy defined as specific IgE positivity against inhalant allergens. We followed the participants by linkage to the Danish National Patient Register (median follow-up time 11.2 years). Hazard ratio (HR) and 95% confidence interval (CI) of autoimmune disease were estimated by Cox regression.

RESULTS

The risk for atopics versus non-atopics was: for any autoimmune disease (HR = 0.99, 95% CI: 0.83, 1.18), thyrotoxicosis (HR = 0.69, 95% CI: 0.34, 1.37), type 1 diabetes (HR = 1.16, 95% CI: 0.84, 1.60), multiple sclerosis (HR = 1.97, 95% CI: 0.95, 4.11), iridocyclitis (HR = 0.82, 95% CI: 0.38, 1.74), Crohn's disease (HR = 1.03, 95% CI: 0.47, 2.25), ulcerative colitis (HR = 0.93, 95% CI: 0.52, 1.69), psoriasis vulgaris (HR = 1.50, 95% CI: 0.86, 2.62), seropositive rheumatoid arthritis (HR = 0.74, 95% CI: 0.48, 1.14) and polymyalgia rheumatica (HR = 0.79, 95% CI: 0.44, 1.44).

CONCLUSIONS

We found no statistically significant associations between atopy and autoimmune disease, but we cannot exclude relatively small to moderate effects - protective or promotive - of atopy on autoimmune disease.