Mononuclear subsets and cytokine profile of venous and capillary blood in patients with psoriasis and healthy people

Abstract

Psoriasis is considered an autoimmune disease with a predominantly cellular mechanism for the development of disorder. Studies in immune pathogenesis of psoriasis were performed either in animal model, which is not just similar to humans, or the data were obtained in patients by means of skin window method, which is traumatic, or by examining venous blood. However, it is difficult to discern parameters of the local immune response in venous blood samples. We have attempted to find an adequate method which would be convenient both for the patient and for the researcher, in order to assess local immune processes occurring in the skin affected by psoriasis. We examined 20 patients with a verified diagnosis of psoriasis, the average age was 44.3 years. The control group included 15 healthy adults, with average age of 46.6 years. Capillary blood was taken by fingerprick, whereas, in psoriatic patients, the samples were taken near the psoriatic lesion at a final volume of 400 μL in two microvettes. Venous blood (3 mL) was taken from the cubital vein into a vacuum tube with EDTA. Clinical analysis of venous and capillary blood was performed in automated hematological analyzer. Immunophenotyping was performed by four-color staining of whole capillary and venous blood followed by lysis of erythrocytes. Cytofluorometry was performed using techniques and reagents from BD Biosciences (USA). Plasma cytokines were determined by multiplex approach (MagPix, BioRad, USA). Upon clinical analysis of blood, the difference between capillary and venous blood was not found, either in healthy group, or among patients with psoriasis. In healthy people, the subsets of mononuclear cells, did not differ between venous and capillary blood. The samples of capillary and venous blood in the patients with psoriasis showed significantly increased levels of double-positive lymphocytes (CD45RA+/CD45R0+), B lymphocytes and NKT lymphocytes (both for relative and and absolute values). A significant increase in the percentage of naive T lymphocytes, activated helpers (Thact) and Treg, as well as B1 cells and Breg, and a significant decrease in B2 lymphocytes was registered in capillary blood of the patients with psoriasis. In venous blood samples from psoriatic patients, only a significant increase in Thact, Treg, and Breg was revealed. In the capillary blood of patients with psoriasis, we found a significant increase in the levels of non-classical M2 monocytes and inflammatory Minfl monocytes, and a decrease in classical M1 monocyte levels; in venous blood of psoriatic patients, only an increase in inflammatory Minfl monocytes was revealed. In capillary blood, all the studied cytokines in psoriasis patients significantly exceeded the levels of corresponding cytokines in healthy controls, except of IL-10. The levels of this cytokine did not differ from healthy group. In venous blood, the levels of most studied cytokines in the group of patients with psoriasis did not differ from the group of healthy ones. Approximately two-fold increase was revealed for IL-4, IL-21, IL-23 and TNF. First, the subsets of mononuclear cells and the cytokine profile of capillary and venous blood of healthy people did not differ significantly. Secondly, our proposed method for determining the subsets of mononuclear cells and capillary blood cytokines profile from the area of psoriatic lesions may be used to monitor local immunity in the patients with psoriasis. This approach is significantly less traumatic than the skin window method and more informative than the studies of venous blood.