Abstract:

Objective To investigate the effect of local hyperthermia on the morphology and quantity of Langerhans cells （LCs） at challenged skin sites of a mouse model of contact hypersensitivity. Methods Sixty mice were equally divided into 3 groups to be treated with local hyperthermia （37 ℃, 39 ℃, 41 ℃ and 43 ℃） for 20 minutes at sensitization sites on the back of mice 3 days before （pre-heat group）, concurrently with （concurrent-heat group） or 2 days after （post-heat group） sensitization respectively. Five mice which remained unsensitized and untreated served as the controls. Five days after the sensitization, the mice were challenged on the dorsal surface of right ears. Two days after the elicitation, the right ears were resected and immunohistochemistry was performed to observe the morphology and determine the quantity of LCs at challenged sites. Results With the rise in temperature, the number of LCs in the epidermis of ear skin decreased in pre-heat group （321.83 ± 41.81, 251.12 ± 16.29, 191.41 ± 28.7, 128.33 ± 77.61 per square millimeter at 37 ℃, 39 ℃, 41 ℃ and 43 ℃, respectively, P < 0.05）, but increased gradually in the concurrent-heat group （309.08 ± 84.69, 355.33 ± 11.38, 405.5 ± 55.25, 438.16 ± 99.56 per square millimeter at 37 ℃, 39 ℃, 41 ℃ and 43 ℃, respectively, P > 0.05） and in the post-heat group （320.83 ± 113.6, 398.33 ± 31.91, 437.83 ± 29.78, 477.25 ± 86.79 per square millimeter at 37 ℃, 39 ℃, 41 ℃ and 43 ℃, respectively, P < 0.01）. The dendrites of LCs increased in number and length when the temperature rose from 37 ℃ to 41 ℃, but slightly declined at 43 ℃. Conclusions Local hyperthermia at sensitization sites could affect the morphology and density of LCs at challenged sites, and the effect is likely associated with the severity of contact hypersensitivity.

Key words: contact hypersensitivity