A Study of LY2127399 in Rheumatoid Arthritis

Inclusion Criteria: * Diagnosis of adult onset RA disease according to revised 1987 American Rheumatism Association (ARA) criteria and currently have a documented history of positive for rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibody (anti-CCP Ab) and have moderately to severely active RA despite ongoing methotrexate (MTX) therapy * Have active RA defined as the presence of at least 8/68 tender and at least 8/66 swollen joints, as determined by the tender joint count and swollen joint count assessment forms * Have a screening C-reactive protein (CRP) measurement greater than 1.2 times upper limit of normal or erythrocyte sedimentation rate (ESR) greater than 28 millimeters/hour (mm/hr) * Have a clinically inflamed joint suitable for synovial biopsy procedure Exclusion Criteria: * Have used an unstable dose of non-steroidal anti-inflammatory drugs (NSAIDs) within 6 weeks prior to baseline * Have used oral corticosteroids at average daily doses of \>10 milligrams/day (mg/day) of prednisone or its equivalent within 6 weeks prior to baseline * Have received any parenteral corticosteroid injection within 6 weeks of baseline * Have used other disease-modifying anti-rheumatic drugs (DMARDs) other than MTX, hydroxychloroquine, and/or sulfasalazine in the 8 weeks prior to baseline