Abstract:

Luan Chao, Chen Hao, Yang Yonghong, Jiang Yiqun, Liu Yi, Chen Min, Wang Baoxi. Hospital of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College; Jiangsu Key Laboratory of Molecular Biology for Skin Diseases and STIs, Nanjing 210042, China Corresponding author: Chen Min, Email: drchenmin@126.com 【Abstract】 Objective To investigate the relationship of CD4+ and CD8+ T cells with melanocytes in skin of patients with psoriasis, and to study their clinical significance. Methods Tissue specimens were obtained from both lesional and nonlesional skin of 29 patients with progressive psoriasis and 5 patients with regressive psoriasis, as well as from normal skin of 6 healthy individuals. Immunohistochemical staining was performed to determine the quantity and distribution of CD4+ T and CD8+ T cells, as well as the quantity of melanocytes and proportion of cells containing pigment granules in the basal layer of these specimens. Statistical analysis was carried out with the software SPSS 18.0 by one-way analysis of variance （ANOVA）, least significant difference （LSD） test and Pearson correlation analysis. Results In patients with psoriasis, the mean number of CD4+ T cells per high-power （× 200） field was significantly larger in lesional skin than in nonlesional skin （epidermis: 5.29 ± 4.66 vs. 0, P < 0.05; dermis: 77.50 ± 43.66 vs. 9.67 ± 7.73, P < 0.05）, so was the mean number of CD8+ T cells per high-power （× 200） field （epidermis: 7.83 ± 6.27 vs. 0.71 ± 1.20, P < 0.05; dermis: 46.08 ± 34.26 vs. 5.54 ± 4.43, P < 0.05）. A significant increase was also observed in the number of CD4+ and CD8+ T cells in lesional skin of patients with psoriasis compared with the normal control skin （both P < 0.05）. The lesional skin of patients with psoriasis also showed significantly increased number of melanocytes （103.45 ± 16.96）, but decreased proportion of pigment granule-containing cells （7.45% ± 3.86%） in the basal layer compared with nonlesional skin （43.62 ± 14.20, P < 0.05; 43.10% ± 14.91%, P < 0.05） and normal control skin （43.33 ± 14.02, P < 0.05; 54.17% ± 29.40%, P < 0.05）. There were no significant differences in either the mean number of CD4+ T cells, CD8+ T cells and melanocytes or the proportion of pigment granule-containing cells between nonlesional psoriatic skin and normal control skin （all P > 0.05）. The mean number of melanocytes was significantly higher in regressive psoriatic lesions than in white patches arising in subsided psoriatic lesions （P < 0.05） and normal control skin （P < 0.05）, but similar between white patches and normal control skin （P > 0.05）, while the proportion of pigment granule-containing cells was insignificantly lower in regressive psoriatic lesions than in white patches （P > 0.05）, and significantly lower in regressive psoriatic lesions and white patches than in normal control skin （both P < 0.05）. Neither the number of CD4+ T cells nor that of CD8+ T cells was correlated with the number of melanocytes or the proportion of pigment granule-containing cells in progressive psoriatic lesions （both P > 0.05）, while the number of both CD4+ T cells and CD8+ T cells was positively correlated with that of melanocytes （r = 0.46 and 0.56, respectively, both P < 0.05）, but uncorrelated with the proportion of pigment granule-containing cells in nonlesional psoriatic skin （both P > 0.05）. Conclusions In progressive psoriatic lesions, there is a significant increase in the number of CD4+ and CD8+ T cells as well as melanocytes in the basal layer, but a significant decrease in the proportion of pigment granule-containing cells. After subsidence of psoriatic lesions, both the number of melanocytes and proportion of pigment granule-containing cells gradually reach the levels in normal skin of healthy individuals.