This study will help the investigators design a method to detect the disease-causing immune cells in patients with rheumatoid arthritis (RA). Such methods are not currently available, but if successful, would help scientists to better understand the causes of RA.

The investigators are interested in learning about the immune cells in the blood that contribute to disease in patients with rheumatoid arthritis (RA). They have developed a method for identifying a specific type of immune cells that can react against normal tissues in the body.

In this study, the investigators will enroll RA patients from the University of Minnesota clinics, collect blood samples from enrolled patients, and process the blood samples to isolate DNA, RNA, serum, and blood cells. They will use the serum to detect whether specific autoantibodies (Anti-cyclic Citrullinated Peptide, or anti-CCP) are present. In cases where anti-CCP antibodies are detected, the investigators may quantify the numbers of immune cells present that contain receptors with the same anti-CCP specificity. They may also test whether the numbers of immune cells with these receptors correlate with measures of disease activity in RA patients.

Inclusion Criteria:

• Diagnosis of rheumatoid arthritis

Exclusion Criteria:

• Use of rituximab immediately prior to visit
• Pregnancy

The investigators will enroll 155 rheumatoid arthritis patients from the University of Minnesota Rheumatology clinics.