Introduction

The relationship between allergic and autoimmune diseases is an important issue, which has recently attracted the researchers’ interest.

Aim

To determine the relationship between atopy and psoriasis.

Material and methods

This case-control study was conducted on 102 patients referred to the Ghaem Hospital, Mashhad, Iran, in 2016. The participants were assigned into two groups: experimental and control groups, including the patients suffering from psoriasis and those with no history of cutaneous or other systemic diseases, respectively. Both groups filled in the ISAAC questionnaire and had skin prick tests. In addition, the serum levels of immunoglobulin E (IgE) and blood eosinophil cell count were measured. The data were analysed using the regression test through SPSS version 16.

Results

According to the results of the ISAAC questionnaire, there was a significant difference between the control and experimental groups in terms of asthma (p = 0.04). The mean serum concentrations of IgE and eosinophil cell count were not significantly different between the experimental (153.93 IU/ml and 187.77 cells/µl, respectively) and control groups (152.19 IU/ml and 187.68 cells/µl, respectively) (p = 0.057 and p = 0.886, respectively). In addition, there was an indirect correlation between the eosinophil cell count and psoriasis severity (p = 0.032, r = –0.297). Furthermore, the comparison of the skin prick test results revealed no significant difference between the two groups regarding the number of positive and negative cases (p = 0.436).

Conclusions

The findings suggested that atopy was not common in the patients with psoriasis and supported the concept that atopy protects against such autoimmune diseases such as psoriasis.