This study will collect white blood cells or plasma (the liquid part of the blood), or both, from healthy volunteers and from patients with rheumatic disorders for research purposes. Rheumatic disorders involve abnormalities of the immune system, the body's defense against disease. The immune system consists of white blood cells such as lymphocytes and monocytes, which produce substances such as antibodies and cytokines. White cells and plasma will be collected through a procedure called apheresis (described below).

Healthy volunteers and patients with confirmed or suspected rheumatic disease who are 18 years of age or older may be eligible for this study. Patients must be participating in a current protocol of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. All candidates will be screened with a history, physical examination, and blood tests for hepatitis B and C and HIV infection. Women of childbearing age will be tested for pregnancy. Routine blood tests will be done in all volunteers, and in patients where needed. Pregnant women and people who test positive for hepatitis or HIV may not participate.

Participants will undergo apheresis to collect lymphocytes, monocytes, or plasma from the blood. For this procedure, a needle is placed in a vein in the arm. Blood flows from the vein through a tube (catheter) into a machine that spins the blood, separating it into its components. The required cells or plasma are extracted, and the rest of the blood, including the red cells and platelets, is returned to the body through the same needle or through a second needle placed in the other arm.

Cells collected from volunteers will be used in studies comparing the number and function of similar cells from patients with rheumatic diseases, focusing on the differences in number and function of the cells in health and disease. Components collected from patients will be used only for studies described in the protocol in which they are currently enrolled.