Exploratory analysis of early changes in peripheral immune cell proportions and clinical response following methotrexate and biologic treatment in rheumatoid arthritis.

OBJECTIVE

To examine the relationships between changes in the proportions of immune cell populations and clinical response at 2 weeks post-treatment with methotrexate (MTX), tumour necrosis factor (TNF) inhibitors, or abatacept, with treatment efficacy at week 12 in patients with rheumatoid arthritis (RA).

METHODS

Peripheral blood samples were collected from 30 patients with RA who received MTX (n=10), a TNF inhibitor+MTX (n=10), and abatacept+MTX (n=10) in this observational study. Of these, 25 patients completed the 12-week follow-up and were included in the efficacy and correlation analyses (MTX n=9; TNF inhibitor+MTX n=8; abatacept+MTX n=8). Immune cell phenotypes were determined using 11-colour flow cytometry at baseline and 2 weeks after drug administration.

RESULTS

Baseline proportions and changes in several immune cell types at 2 weeks post treatment correlated with the efficacy of arthritis treatment at week 12. Specifically, a higher baseline proportion and a greater decrease at week 2 in class-switched memory B cells following MTX administration were significantly associated with treatment efficacy for arthritis, as were the same changes in activated Th1 cells following abatacept administration. Increases in effector memory CD8+ T cells were also significantly correlated with the efficacy of TNF inhibitor treatment in RA patients.

CONCLUSION

This exploratory study identified a potential association between baseline or early changes in immune cell populations and subsequent clinical responses in RA.