The purpose of this study is to estimate the effect of anakinra, 100 mg once daily (QD), on the development of an anti-tetanus antibody response in subjects with RA after vaccination with a tetanus and diphtheria toxoids injection. In addition, this study will evaluate the general safety profile of therapy with anakinra, 100 mg QD, in subjects with RA after vaccination with a tetanus and diphtheria toxoids injection.

Inclusion Criteria: - Diagnosed with RA by American College of Rheumatology (ACR) criteria for greater than or equal to 12 weeks - Active RA with at least 3 swollen joints and 3 tender/painful joints and at least one of the following:

• Morning stiffness greater than or equal to 45 minutes;
• C-reactive protein (CRP) greater than or equal to 1.5 mg/dL;
• Erythrocyte sedimentation rate greater than or equal to 28 mm/hr;
• Stable methotrexate dose of less than or equal to 20 mg/week for 8 weeks prior to randomization;
• Stable doses of nonsteroidal anti-inflammatory drugs (NSAIDs) and oral corticosteroids (less than or equal to 10 mg/day of prednisone or equivalent) for 4 weeks prior to randomization. Exclusion Criteria: - Pregnant or breast-feeding women - Any uncontrolled, clinically significant systemic disease - Has total white cell count less than 3.5 x 10^9/L, a neutrophils count less than 2.0 x 10^9/L, platelet count less than 125 x 10^9/L or hemoglobin (Hgb) less than 8.0 g/dL at screening - Abnormal liver function tests (AST/ALT greater than or equal to 1.5 x the upper limit of normal at screening) - Serum creatinine greater than 1.5 x the upper limit of normal at screening - Subject recall of having tetanus toxoid or diphtheria vaccination less than 10 years prior to randomization - Has never received a primary tetanus vaccination - Any other vaccination within 12 weeks of randomization - Disease-modifying antirheumatic drugs (DMARDs) other than methotrexate - Biologics to treat RA within the previous 8 weeks of screening (e.g., etanercept, infliximab) - Subjects were treated with anakinra within 4 weeks prior to randomization