Objective To study the influence of sunscreens with different efficacy on delayed type hypersensitivity (DTH) and their immunoprotective effect in mice.Methods A cohort of mice were randomly divided into 5 groups with 10 mice in each group:group 1 as the positive control without irradiation,group 2 receiving solar-simulated radiation (SSR) only,group 3 receiving SSR and protected by sunscreen l with sun protection factor 15(SPF15)and persistent pigment darkening(PPD)12,group 4 receiving SSR and protected by sunscreen 2 with SPF 50 and PPD 28,and group 5 as the negative contml receiving SSR only.SSR was carried out on the back of mice with the UVA dose being 1.4 J/cm2 and UVB dose being 100 mJ/cm2 for 10 days.After a 5-day irradiation,the groups 1 to 4 were immunized by intraperitoneal injection with 100 μl(107 cells/ml) of Candida albicans suspension.On the 10th day both sides of the posterior foot pad were measured;then the foot pads were injected with additional 50 μl of the Candida albicans suspension.Twenty-four hours after the injection,the thickness of each foot pad was measured,and immunosuppression rate was calculated.Finally,the mice were sacrificed and skin samples were obtained from the back of these mice followed by the examination of CDla, CD80 and CD86 expression by Western blot.Resets The thickness of edema in foot pads was 0.41±0.38 mm,0.21±0.23 mm and 0.30 ± 0.25 mm in group 1,3 and 4,respectively,significantly higher than in group 5 and 2(0.04±0.03 mm,0.14±0.12 mm,respectively,all P<0.05),while no significant difference was observed between the group 3 and 4(P>0.05).Significant differences were observed in the immunosuppression rate between group 2,3 and 4(73.0%±11.3%,54.1%±6.4%,29.7%±7.5%,respectively,all P<0.01).Western blot revealed a significant increment in the expression of CDla protein in group 1 compared with group 2 as well as in the expression of CD86 protein in group 1 and group 3 compamd with group 2 and group 5(all P<0.05),but no statistical difference was observed between the other groups in the expression level of CDla,CD80 or CD86(P>0.05).Conclusions The exposure to sub-erythema dose of UV can induce DTH,and sunscreens have an immunoprotective effect in this process.Epidermal Langerhans cells are not essential for UV-induced immunosuppression.

Objective:To analyze the risk factors of postinflammatory hyperpigmentation (PIH) after laser in the treatment of acquired bilateral nevus of Ota-like macules (ABNOM).Methods:A retrospective study was conducted to follow up 120 patients with acquired bilateral nevus of Ota-like macules in the Department of Laser and Physiotherapy, Guangzhou Institute of Dermatology between January 2011 and December 2018, which accepted 1064-nm Q-switched neodymium: yttrium-aluminum-garnet laser treatment. The difference was analyzed between different age, sex, clinical classification, Fitzpatrick skin classification, ABNOM with melasma and postinflammatory pigmentation after laser treatment. Logistic regression was used to analyze the risk factors of postinflammatory hyperpigmentation after 1064-nm Q-switched neodymium: yttrium-aluminum-garnet laser treatment of acquired bilateral nevus of Ota-like macules.Results:Fifty-three ABNOM patients (44.17%) developed PIH after laser treatment. Univariate analysis showed that age, clinical classification, Fitzpatrick skin classification and the patients with both ABNOM and melasma all affected the occurrence of PIH after laser in the treatment of ABNOM, and the difference was statistically significant ( P<0.01). Logistic regression showed that older age, more severe clinical classification and the presence of ABNOM with melasma were the risk factors of PIH after treatment of ABNOM. Conclusions:ABNOM patients should be treated as early as possible. The risk of inducing PIH is great after laser treatment in patients with more severe clinical classification and patients with both ABNOM and melasma.