Assessment of CLA+T-cell subpopulations in the blood of patients with chronic dermatoses

Background. CLA⁺T-cell are an important component of skin-associated lymphoid tissue, and thus determine the pathogenesis of many immuno-mediated dermatoses.

Aims. Determine the relative number of CLA⁺T-cell subpopulations in the peripheral blood of patients with psoriasis, lichen planus and atopic dermatitis, as well as assess their impact on the severity of dermatoses.

Materials and methods. We examined 82 patients with psoriasis aged 19 to 62 years, 54 patients with lichen planus (LP) aged 18 to 54 years, 44 patients with atopic dermatitis (AD) aged 18 to 44 years, as well as 20 practically healthy individuals aged 18 to 52 years who were admitted to the clinic for the removal of benign skin neoplasms.

All patients underwent a standard clinical examination with the determination of indicators that characterize the severity of dermatosis: PASI (Psoriasis Area and Severity Index) — for patients with psoriasis, IPSLP (index of prevalence and severity of lichen planus) — for patients with lichen planus and SCORAD (Scoring of Atopic Dermatitis) — for patients with atopic dermatitis. Defining subpopulations CLA⁺T-lymphocytes were carried out on a flow cytometer «Cytomics FC500» by Beckman Coulter using appropriate combinations of direct monoclonal antibodies and isotopic controls. The groups were compared using the nonparametric Mann — Whitney test, and the differences were considered significant at p<0,05. To analyze the relationship between the severity of dermatosis and the relative content of subpopulations CLA⁺T-cells used Spearman's rank correlation coefficient.

Results. In patients with psoriasis, a significant increase in the percentage of the total number of T-lymphocytes positive for CLA (CLA⁺CD3⁺) and T-helpers positive for CLA (CLA⁺CD4⁺) (p=0,002 and 8,5×10^–4, respectively), in patients with PL and AD only CLA⁺CD4⁺ lymphocytes (p=0,028 and 0,003, respectively). In the progressive period of psoriasis, a direct moderate correlation was found between the circulating subpopulation of cytotoxic T lymphocytes positive for CLA (CLA⁺CD8⁺) and the PASI index (r_s=0,47; p<0,001), in the acute period of AD — between the CLA⁺CD3⁺ subpopulations and CLA⁺CD4⁺ cells and the SCORAD index (r_s=0,53; p < 0,001 and r_s=0,57; p<0,001, respectively). In PL, the severity of the course of dermatosis was not accompanied by any significant changes in the CLA-positive T-cell subpopulations.

Conclusion. The results of the study confirmed the important role of CLA⁺T cell subpopulations in the development of chronic dermatoses. In all groups (psoriasis, LP and AD), an increase in the relative number of CLA⁺CD4⁺ T-helpers was noted compared with the control group. The relationship between the severity of psoriasis and the relative number of CLA⁺CD8⁺ cytotoxic T-lymphocytes, and the severity of AD — with CLA⁺CD3⁺ and CLA⁺CD4⁺ T-helpers is also shown.