Atopic dermatitis and systemic autoimmune diseases: a descriptive cross sectional study.

Atopic dermatitis (AD) has a Th2 (T-helper 2) immune-reactivity pattern. However, the majority of systemic autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis, and insulin dependent diabetes mellitus show a Th1 (T-helper 1) reactivity pattern. From this, one may hypothesize that AD and the Th1 autoimmune diseases could be inversely associated and AD may be more common in the minority of autoimmune diseases with a Th2 overactivity pattern such as systemic lupus erythematosus. A cross sectional study was designed. Our patients were enrolled from a general university hospital (all systemic autoimmune patients in every medical ward based on definite diagnoses in their medical records). Information on atopic dermatitis was obtained by questionnaires and physical examination by a dermatologist. A total of 63 patients were studied; 17.5 percent of cases had atopic dermatitis in the past or present. There were 31 patients 49.2 %) who carried a diagnosis known to be associated with Th1 reaction, and 21 patients (33.3 %) who had a disease associated with Th2-type reactivity. In 11 patients (17.5 %) the T-cell reaction type was not definitively classified. The relative frequency of AD was 9.7 percent (3 of 31 cases) in Th1-related autoimmune diseases, 28.6 percent (6 of 21 cases) in Th2-related autoimmune diseases and 18.2 percent (2 of 11 cases) in the unclassified category, a difference not statistically significant. Although the power of this study is not high enough to show a statistical significance, AD seems to be uncommon in patients with autoimmune diseases associated with Th1 overactivity.