Lymphocyte profile and expression of PD-1 and Tim3 on T cells differentiate sarcoidosis from acute inflammation.

Sarcoidosis (SA) is a chronic, inflammatory disease in which the immune system overreacts, causing groups of cells to form granulomas. Lymphocytes play an important role in forming granulomas. However, the role of individual population in the development of inflammatory changes is still unknown. The aim of the study was to compare the lymphocyte profile and expression of immunomodulatory molecules on T cells in peripheral blood (PB) of SA patients and in PB of patients with inflammation caused by SARS-CoV-2 virus. PB samples from 25 SA patients, 30 COVID-19 patients and 25 healthy controls (HC) were collected. Following lymphocytes subpopulations were determined by flow cytometry: CD4+ T cells, Th17 cells, Tregs, CD8+ T cells. Additionally, B cells and T cells maturation profile was assessed. Moreover, expression of PD-1, Lag3 and Tim3 on CD4 and CD8 T cells was determined. We reported that SA patients had significantly higher percentage of: Th17 cells, CD4 CD45RO+ cells, Tregs and non-switched B cells than COVID patients and HC. Interestingly, SA patients presented significantly lower percentage of CD8 CD45RO+, central memory CD4 cells, effector CD8 cells and plasmoblasts than COVID patients and HC. Surprisingly, SA patients had higher percentage of PD-1+ CD4 T cells, Tim3+ CD4 T cells and PD-1+ C8 T cells, but lower percentage of Tim3+ CD8 T cells than COVID patients. Our results show that lymphocyte maturation profile is different in SA patients and COVID patients. Higher expression of immunosuppressive molecules on T cells in SA patients imply T cells anergy. Altogether, above results may suggest differences in the pathogenesis of acute and chronic inflammation.