Alterations in peripheral blood CD8+T cell subsets in patients with lung sarcoidosis

Sarcoidosis is a systemic inflammatory disorder of unknown etiology characterized by tissue infiltration with macrophages and lymphocytes, including CD8 + T cells, and associated non-caseous granuloma formation. The aim of the study was to investigate various peripheral blood CD8 + T cells from patients with chronic respiratory sarcoidosis using markers of T cell maturation and ‘polarization’. Peripheral blood samples were collected from 34 patients with newly diagnosed chronic sarcoidosis of respiratory organs with the background of a natural course of disease, and without a history of immunosuppressive therapy. The diagnosis of pulmonary sarcoidosis was performed according to the standard criteria and was confirmed by histological examination for 94.1% of patients. Peripheral venous blood samples from healthy, gender- and age-matched volunteers (n = 40), were used as control specimens. Multicolor flow cytometry revealed that patients with sarcoidosis had decreased levels of CD45RA + CD62L + ‘naïve’ and CD45RA - CD62L + central memory CD8 + T cells as compared with healthy controls. Moreover, the frequencies of ЕМ1 (CD45RA - CD62L - CD27 + CD28 + ) and pre-effector type 1 (CD45RA + CD62L - CD27 + CD28 + ) cells were also reduced. In order to assess the relevant ‘polarized’ CD8 + T cell subsets, we have specified the Tc1 (CCR6 - CXCR3 + ), Tc2 (CCR6 - CXCR3 - ), Tc17 (CCR6 + CXCR3 - ), and double-positive Tc17.1 (CCR6 + CXCR3 + ) cell populations. The relative and absolute numbers of CXCR3-expressing CD8 + T cell subsets (Tc1 and Tc17.1 were found to be significantly decreased in patients with sarcoidosis if compared to healthy controls. By contrary, Тс2 CD8 + T cell contents were significantly elevated. Furthermore, the relative numbers of Tc1 cells negatively correlated with serum ACE levels (r = -0.456; р = 0.01), whereas Тс2 levels positively correlated with serum ACE levels (r = 0.623; р < 0.001). Thus, our results indicate that CD8 + T cells may play a role in pathogenesis of sarcoidosis. More extensive clinical and immunological comparisons are required for further systematization of the obtained data.