D3.339 - Assessment of the immune status of systemic sclerosis patients by flow cytometry

Systemic sclerosis (SSc) is a rheumatic disease characterized by dysfunction of innate and adaptive immunity, including cell contents and functions. The aim of this study was to assess the state of the immune system in SSc patients versus healthy donors (HD).

The immune parameters of peripheral venous blood of 23 patients with SSc and 21 HD were compared. Subsets of CD45⁺CD14^– T-cells (CD3+CD4+ T-helpers, CD3⁺CD8⁺ cytotoxic cells, CD3⁺HLA-DR⁺ activated T-cells, CD4⁺/CD8⁺ TCM (CD62L⁺CD45RA^–), CD4⁺/CD8⁺ NAÏVE (CD62L⁺CD45RA⁺), CD4⁺/CD8⁺ TEM (CD62L^–CD45RA^–), CD4⁺/CD8⁺ TEMRA(CD62L^–CD45RA⁺),TIM3⁺ Exhausted, PD-1⁺ Exhausted, СD19⁺ B-cells, CD16⁺CD3^–  NK-cells, CD16⁺CD3⁺ NKT-cells, HLA-DR^–Lin⁺CD11b⁺CD15⁺CD141⁺ G-MDSC, subsets of monocytes (CD14^–CD16⁺ nonclassical, CD14⁺CD16^– сlassical, CD14⁺CD16⁺ intermediate) and subsets of dendritic cells (DC) (CD1c⁺ and CD141⁺ HLA-DR⁺Lin^–CD123^–CD11c⁺ mDC, HLA-DR⁺Lin^–CD123⁺CD11c^– pDC) were analyzed by flow cytometry.

There was no significant differences in the absolute counts of subsets of T-cells (CD4⁺TCM, CD8⁺/CD4⁺TEM, CD4⁺TEMRA, activated T-cells, TIM3⁺Exhausted), subsets of DC (pDC, mDC, CD1c⁺mDC). PD-1⁺T-cells (HD:0.06(0.04-0.11),SSc:0.56(0.15-1.68), p=0.00), G-MDSC (HD:0.003(0.002-0.005),SSc:0.02(0.01-0.05),p=0.00) was significant higher in SSc group compared to HD. The absolute count of lymphoid cells (CD3⁺cells, T-helper cells, cytotoxic lymphocytes, CD8⁺TCM, Treg, В-lymphocyte, NK, NKT) and myeloid cells (CD141mDC) was less in SSc compared to HD. CD8⁺NAÏVE (HD:0.11(0.08-0.20),SSc:0.03(0.01-0.06),p=0.00), CD8⁺TEMRA (HD:0.11(0.07-0.15),SSc:0.05(0.02-0.08),p=0.00), CD4⁺NAÏVE (HD:0.25(0.14-0.33),SSc:0.04(0.02-0.08),p=0.00), subsets of monocyte: сlassical (HD:1.04(0.58-1.39),SSc:0.08(0.03-0.11),p=0.00), nonclassical (HD:0.05(0.03-0.07),SSc:0.00(0.00-0.00),p=0.00), intermediate (HD:0.20(0.13-0.34),SSc:0.01(0.01-0.02),p=0.00) was significantly less in SSc compared to HD.

The increase of absolute counts of PD-1⁺T-cells and G-MDSC in the patients with SSc indicates immune system exhaustion suggesting the direction which should be taken to search for ways to correct immune dysfunction in this disease.