Inflammatory involvement of cervical spine ligaments in patients with rheumatoid arthritis and atlantoaxial subluxation.

The inflammatory involvement of cervical spine ligaments in patients with rheumatoid arthritis (RA) with atlantoaxial subluxation was studied. Biopsy specimens were obtained from the ligament structures between the posterior arch of the atlas and the spinous process of C2 during atlantoaxis stabilizing operations. Inflammatory cells in cryostat sections were stained in situ using monoclonal hybridoma antibodies applied in a sensitive avidin-biotin-peroxidase complex (ABC) method. In 4 of 8 ligament specimens, focal inflammatory cell infiltrates consisting mainly of T11 + T lymphocytes (77 +/- 9%) and M1 + monocytes (21 +/- 6%) were found. The occurrence of lymphocyte activation markers Ia, 4F2 and T9, 46 +/- 8%, 38 +/- 10% and 14 +/- 5%, respectively, suggests active involvement of the lymphocytes in the local immune inflammation. Our findings suggest a mechanism eventually leading to slackening of the cervical spine ligamentous apparatus and atlantoaxial subluxation in RA.