The role of the immune system of the skin in the pathogenesis of psoriasis
The skin of patients with psoriasis is regarded as an ectopic lymphoid organ with dominating T-cell zones, where the recruitment of naive lymphocytes, their proliferation and antigen-specific differentiation in mature T cells may take place. The goal of the study was to examine the subpopulations of dendritic cells and lymphocytes in the skin of psoriasis patients in different periods of the disease. Material and methods: the study involved 32 patients with biopsy specimens of skin psoriasis vulgaris in the progressive period and in the remission, and 15 healthy people. Skin biopsies were stained immunohistochemically using anti-CD1a, -CD3, -CD4, -CD5, -CD8, -CD11c, -CD20, -CD23, -CD45RA, -CD45RO, -CD79a, -CD83, -CD207, -bcl2, -FOXP3, -IL17A, -Ki67, -CD3e–Ki67, -pax5 antibodies. Results: data showed a manifold increase in the number of dendritic cells and T-lymphocytes in the affected skin of psoriasis patients in the progressive period and in the remission, compared with healthy individuals. About 10% of the subpopulation of T cells in the skin of psoriasis patients were represented by CD45RA+-lymphocytes. High expression of Ki67 protein in cells of the dermal infiltrate psoriatic papules was observed. It was found that about one-third of proliferating cells of the dermis of patients with psoriasis in the progressive period are T-lymphocytes (CD3e+Ki67+). Conclusions: the findings suggest the possibility of proliferation of T lymphocytes in the skin of psoriasis patients in the progressive period of the disease.