Rheumatoid arthritis (RA) is a chronic autoimmune disease and it is known that lymphocytes play a major role in its pathogenesis. However, there have been no comprehensive studies on the changes in peripheral blood lymphocyte (PBL) subpopulations expressing different clusters of differentiation (CD) in patients with long-lasting RA.
The aim of our study was to measure the main subpopulations of PBL, expression of costimulatory marker CD28, and activation status of CD4+ T cells depending on clinical disease activity in long-lasting RA.
The study comprised 60 patients with RA and 19 healthy volunteers. Disease activity, the proportion and number of the main PBL subpopulations (T, B, natural killer [NK], and NK T cells [NKT]), the expression of costimulatory marker CD28, and the activation status of CD4+ T cells were evaluated on the same day. A multicolor flow cytometry with marked monoclonal antibodies was used for the assessment of lymphocyte subpopulations.
The percentage of CD3+CD4+, NKT, CD4+CD28-, CD8+CD28-, CD4+CD69+, CD4+CD25+, and CD4+HLA-DR+ was significantly higher in RA compared with the control group. A higher proportion of CD4+CD28- was associated with more active disease, while an inverse correlation was observed for B cells. The proportion of CD4+CD28- was not associated with disease activity. The number of CD4+CD69+ cells in RA patients increased with increasing DAS28, while the number of CD4+HLA-DR+ T cells showed no such association.
Our results have shown for the first time an association between the phenotype patterns of PBL T, B, and NKT and RA activity in patients with long-lasting disease, which reinforces the hypothesis that PBL play an important role in modifying or maintaining the disease activity.