Absence of autoimmunity to type II collagen in generalised nodal osteoarthritis

A cardinal feature of generalised nodal osteoarthritis is the loss of articular cartilage. To determine if autoimmunity to these cartilage collagens occurred, serum antibodies to native and denatured type II collagen were measured by enzyme linked immunosorbent assay (ELISA) in 96 patients (90 women, six men, aged 47-91 years) with generalised nodal osteoarthritis. Generalised nodal osteoarthritis was diagnosed by typical clinical and radiological features. Serum samples from 42 blood donors were assayed as controls. No significant difference was found between the patients with generalised nodal osteoarthritis and the controls. Furthermore, the 20 patients who were HLA-A1, B8 positive had similar antibody levels to the group as a whole. One woman patient with generalised nodal osteoarthritis (HLA-A1, B8 negative) had markedly increased antibody levels to native and denatured type II collagen in a pattern similar to that seen in patients with rheumatoid arthritis. This patient did not develop super added rheumatoid arthritis during a three year follow up period. Autoimmunity to type II collagen is therefore rare in generalised nodal osteoarthritis. A lack of collagen antibodies in a condition characterised by hyaline cartilage loss suggests that the presence of such antibodies in rheumatoid arthritis is more than a secondary event to joint damage.