Not too long ago, I wrote about the utility of the Rheumatoid Factor (RF) and the anti-cyclic citrullinated peptide (anti-CCP) antibody in diagnosing and prognosing rheumatoid arthritis. RF remains the granddaddy of the antibodies associated with rheumatoid arthritis, and is the only autoantibody included in the American College of Rheumatology (ACR) classification criteria for rheumatoid arthritis. However, anti-CCP antibodies are being used more frequently in the work-up of patients with rheumatoid arthritis, or suspected rheumatoid arthritis.
There is another antibody, the anti-Sa antibody, which has been associated with more destructive rheumatoid arthritis compared to RF and anti-CCP. Interestingly, this anti-Sa antibody has reactivity similar to the anti-CCP antibody. A paper published in the January, 2008 issue of Arthritis and Rheumatism studied a modified version of the anti-Sa antibody, known as anti-MCV, and compared it to anti-CCP antibodies in patients with early rheumatoid arthritis.
The study showed that the anti-MCV antibody was a more sensitive test compared to the anti-CCP antibody. But both of these tests, if positive at the time of diagnosis, were associated with more severe disease compared to patients who were not found to be positive for these antibodies. Anti-MCV antibodies are associated with more joint destruction on x-ray.
Interestingly, the anti-MCV level appeared to correlate with the amount of disease activity. But there was not such an impressive correlation with anti-CCP levels. And, of course, it is well known that RF does not correlate very well with disease activity either.
It remains to be seen if the anti-MCV antibody will be found almost exclusively in rheumatoid arthritis patients. Initially, the anti-CCP antibody was thought to be found only in rheumatoid arthritis patients, but over the years we have seen anti-CCP present in other illnesses, including patients with juvenile arthritis and patients with psoriatic arthritis.
There are many other auto-antibodies that target different components of the joints, and these will have to be studied also. It remains to be seen if these can be helpful in determining more aggressive rheumatoid arthritis in the future when a patient first presents to his or her rheumatologist.
With the rising cost of medicines, rheumatologists could benefit from tools which help them to decide when and if to be aggressive with treatment early in the course of rheumatoid arthritis. And with the rising costs in time lost from work and the stress of having a painful chronic illness, patients could also benefit from such tools.
We will have to continue to watch the research. The anti-MCV antibody is an interesting one, for sure. But it is too early to tell whether this will be of practical benefit in rheumatoid arthritis.
Published On: February 06, 2008