Effect of solar irradiation on serum specific immunoglobulin E to house-dust mite

The relationship between sensitization to Dermatophagoides species and solar irradiation, as reflected by vitamin D, remains elusive.

We investigated the lag time and the cumulative and maximum effects of exposure to solar irradiation on sensitization to house-dust mites.

A time series study design was applied to solar irradiation (MJ/m(2)) and relative humidity (%) for specific immunoglobulin E (IgE) levels against Dermatophagoides pteronyssinus (n = 20,451) and Dermatophagoides farinae (n = 22,824). We used the distributed lag nonlinear model to assess the difference of log IgE to house-dust mites in relation to climate variables.

Compared with specific IgE levels of those exposed to 18 MJ/m(2), the maximum increase in sensitization to D. pteronyssinus was observed at a solar irradiation of 10 MJ/m(2) at peak 0 week (difference of log IgE 0.368 [95% confidence interval (CI), 0.209-0.529], p < 0.001), and this increase continued for 3 weeks. The IgE level was significantly affected by the relative humidity of the 3rd- to 12th-lag week, and the effect reached its peak at 75% on the 8th week (difference of log IgE 0.394 [95% CI, 0.221-0.566], p < 0.001). The logistic regression analysis showed that solar irradiation was associated with a decreased risk to sensitization to D. pteronyssinus (odds ratio 0.988 per 1 MJ/m(2) [95% CI, 0.979-0.997], p < 0.013) on the testing week after controlling for humidity and temperature.

This study demonstrated that low solar irradiation immediately increased the risk of sensitization to two house-dust mite species. Further research is warranted to delineate the underlying mechanism of the effect of solar irradiation on aeroallergen sensitization.