Number and phenotype of rheumatoid arthritis patients' CD4+CD25hi regulatory T cells are not affected by adalimumab or etanercept

Objective. To analyse the therapeutic effects of etanercept (ETA) or adalimumab (ADA) on the numbers and phenotypes of CD4(+)CD25(hi) Tregs in RA patients. Methods. RA patients received ADA (n = 28) or ETA (n = 20) and stable-dose MTX or LEF. Therapeutic responses were assessed with the 28-joint DAS (DAS-28) criteria after 12 weeks of treatment. Treg numbers and phenotypes, determined by flow cytometry using different gating strategies, were compared between responders and non-responders before and after 6 and 12 weeks of treatment. Results. The percentages of good, moderate and non-responders among patients given ADA or ETA, respectively, were 46.5, 35.7 and 17.8% or 30, 20 and 50%, with respective mean (s.d.) pre-treatment CD4(+)CD25(hi) Treg percentages of 5.5 (0.04)% or 4.95 (0.02)%. Overall, for patients with active RA given ADA or ETA, neither TNF-alpha-blocking agent had an effect on Tregs percentage and absolute number. Moreover, CD4(+)CD25(hi) Treg counts remained unaffected in RA responders to ADA or ETA, compared with RA non-responders. Furthermore, the CD4(+)CD25(hi)CD45RA(+), CD4(+)CD25(hi)CD45RO(+) and CD4(+)CD25(hi)CD62L(+) cell populations were unchanged by TNF-alpha-blocking agents. Conclusion. Neither ADA nor ETA modified the percentages or absolute numbers of circulating CD4(+)CD25(hi) Tregs and their phenotypes after being administered for 6 and 12 weeks to RA patients.