The behavior of a newly described acute-phase protein in inflammatory joint disease.

Rho, a newly characterized acute-phase protein, was present in high titer in a group of 109 patients with various rheumatic diseases. Statistically significant titer elevations were demonstrated in patients with rheumatoid arthritis (RA), ankylosing spondylitis, and gout. In individual RA patients, serial titers failed to correlate with disease activity or with rheumatic seropositivity. The natural behavior ofrho antigen is contrasted with that of C-reactive protein. Comments are made regarding the possible association of rubella infection with rheumatoid arthritis.