Hypothesis generating study to identify the changes in synovial tissue early after initiation of infliximab therapy

1. RA patients with active disease at baseline assessed by the DAS28;

2. Be =>18 years of age;

3. Use concurrent methotrexate treatment (7.5-30 mg/week; stable since =>28 days before initiation) during the study. Subjects may be taking nonsteroidal anti-inflammatory drugs, provided the dose and frequency have been stable for at least 28 days. Subjects may be receiving prednisone therapy <=10 mg/day provided that the dosage has been stable for at least a months prior to entry.

1. Pregnancy;

2. Breastfeeding;

3. A history of or acute inflammatory joint disease of different origin e.g. mixed connective tissue disease, seronegative spondyloarthropathy, psoriatic arthritis, Reiter¡¯s syndrome, systemic lupus erythematosus or any arthritis with onset prior to age 16 years;

4. Acute major trauma;

5. Previous therapy at any time with:

a. TNF-directed monoclonal antibodies
p75 TNF receptor fusion protein;

6. Therapy within the previous 45 days with:

a. any experimental drug;

b. alkylating agents, e.g. cyclophosphamide, chlorambucil;

c. anti metabolites;

d. monoclonal antibodies;

e. growth factors;

f. other cytokines;

7. Therapy within the previous 28 days with:

a. parenteral or intraarticular corticoid injections;

b. oral corticosteroid therapy exceeding a prednisone equivalent of 10 mg daily;

c. present use of DMARDs other than methotrexate;

8. Fever (orally measured > 38 ¡ãC), chronic infections or infections requiring anti-microbial therapy;

9. Manifest cardiac failure (stage III or IV according to NYHA classification);

10. Progressive fatal disease/terminal illness;

11. A hematopoietic disease;

12. Body weight of less than 45 kg.