rheumatoid factor

noun Biochemistry.

1. an antibody that is found in the blood of many persons afflicted with rheumatoid arthritis and that reacts against globulins in the blood.

n.

1. Any of the immunoglobulins found in the serum of individuals with rheumatoid arthritis that enhance the agglutination of suspended particles that are coated with pooled human gamma globulin and that are used to diagnose the disease.