*4.1. Inclusion and Exclusion Criteria*

The study subjects included 47 Caucasian patients with ACR/EULAR (American College of Rheumatology/The European League Against Rheumatism) 2010 classification criteria for RA [44]. Patients were studied in parallel with 29 healthy sex-, age-, ethnicity-matched controls. The patients were followed at the Rheumatology Service, Hospital Príncipe de Asturias, Alcala University, in Spain. All patients provided their informed consent to be included. The study was properly approved by the hospital's clinical/ethics committee: "Ethical committee for clinical research of the Hospital Principe de Asturias" (research proyect 1/2006, code P1-11-02433, committee approval date 26/1/2006).

Inclusion criteria:

Patients with new-onset RA (disease duration < 3-months), previously untreated with DMARDs and a disease activity score of 28 (DAS28) according to EULAR criteria, were evaluated for inclusion in the study [44].

Exclusion criteria:

To have (1) severe cardiovascular disease, (2) hypercholesterolemia or diabetesmellitus, hematopoietic, (3) lung, hepatic or renal disorders, (4) acute or chronic bacterial or viral infections, (5) other autoimmune diseases, (6) treatment with steroids, immunosuppressors or other drugs that would have interacted with the immune system in the previous 6 months, (7) possible pregnancy/lactation during the study period, and (8) simultaneous malignancy or congenital immunodeficiency.
