Immune system in rheumatoid arthritis: possible implications in neoplasms.

Although the immune system in rheumatoid arthritis is generally in a state of hyperactivity, deficient function can be demonstrated in certain specific parts of the system. This has been most clearly demonstrated in studies of the response of blood lymphocytes from demonstrated in studies of the response of blood lymphocytes from patients with rheumatoid arthritis to in vitro infection by the Epstein-Barr virus. The virus normally infects B cells promoting proliferation. This results in the establishment of permanent lines of infected B cells more commonly than normal in rheumatoid arthritis. This condition is associated with decreased production of lymphokines, interleukin-2, and gamma interferon. Similar in vitro problems in immune responses to other antigens have also been described. Although natural killer cells are scarce among synovial cells, they are present in normal numbers in the blood. Whether these select immunodeficiencies make patients with rheumatoid arthritis more prone to neoplasms, particularly lymphomas, is a question that has not been investigated until now. Nor has it been determined whether the immune abnormalities in rheumatoid arthritis make patients more prone to neoplasms from the therapeutic agents used in their treatment.