A detailed quantitative analysis of circulating T peripheral and follicular helper lymphocytes in patients with rheumatoid arthritis and systemic lupus erythematosus

Introduction and objective

Peripheral and follicular helper T lymphocytes (Tph and Tfh, respectively) have an important role in B cell immune responses and the pathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Although several studies on the number of Tph and Tfh cells in these conditions have been published, different phenotypes have been employed for their analysis. In this study, we assessed the levels and function of Tph and Tfh cells in blood samples from patients with RA and SLE by using an extended immunophenotype.

Materials and methods

In a cross-sectional pilot study, blood samples from twenty-seven patients with RA and fifteen with SLE, and twenty-six healthy controls were studied. The levels of Tph (CD4⁺PD-1⁺CXCR5⁻CD38⁺CD69⁺ICOS⁺) and Tfh (CD4⁺PD-1⁺CXCR5⁺CD38⁺CD69⁺ICOS⁺) cells were analyzed by flow cytometry. In addition, the function of Tph/Tfh cells was estimated by measuring the synthesis of IL-21 by these lymphocytes as well as the number of circulating plasmablasts (CD19⁺CD27⁺CD20⁻CD38^hi).

Results

Increased percentages of Tph and Tfh lymphocytes were detected in patients with RA and SLE. Furthermore, the synthesis of IL-21 tended to be higher in both conditions, and higher levels of plasmablasts were detected in these patients, compared to controls. In patients with SLE, the number of Tph cells was associated with disease activity and with the levels of circulating plasmablasts, whereas in patients with RA a significant correlation between Tph cells and evolution time was observed.

Discussion and conclusions

Our data of Tph and Tfh lymphocytes, based in the analysis of an extended phenotype of these cells, provides further evidence on their involvement in the pathogenesis of RA and SLE.