Fcγ receptor expression on monocytes and association with etanercept efficacy in rheumatoid arthritis: a prospective cohort study

Background To investigate whether Fcγ receptors (FcγRs) expression on peripheral blood monocytes predicts clinical response to etanercept in rheumatoid arthritis (RA). Methods In this prospective cohort study, FcγRs expression on peripheral blood monocyte subsets was analyzed by flow cytometry. The primary outcome was the change in DAS28-CRP from baseline to week 12. The secondary outcome was the change in DAS28-ESR. Results Following etanercept therapy, the proportion of FcγRI-positive monocytes and classical (CD14 ++ CD16 − ) monocytes was reduced, while the proportion of non-classical (CD14 + CD16 ++ ) monocytes was increased. Changes in intermediate monocytes (CD14 ++ CD16 + ) were positively correlated with both DAS28-CRP change and DAS28-ESR change at week 24 after etanercept therapy. Patients with high intermediate (CD14 ++ CD16 + ) monocytes showed significantly greater reductions in DAS28-CRP at week 12. Conclusion Intermediate monocytes (CD14 ++ CD16 + ) were correlated with improvements in DAS28-CRP achieved by week 12 following etanercept therapy. RA patients with low intermediate monocytes may derive less benefit from etanercept treatment.