What do you know about antibodies to collagen type II?
Collagens are components of the extracellular matrix. Collagen type II is the major collagen in articular cartilage.
The value of the antibody determination is limited: the prevalence of anti-collagen-antibodies is relativeley low in RA-sera and they are not uncommonly found in many other diseases. Thus, specificity and sensitivity of type II anti-collagen antibodies for RA are low.
Neither the occurrence of serum autoantibodies to native nor denatured type II collagen is specific for RA, but synovial fluids of RA patients, compared to controls, contain anti-collagen antibodies in higher frequencies and amounts. Probably, the determination of anti-collagen antibodies in synovial fluid is of greater value than in serum.
Whenever antibodies to collagen are found, immunological cross-reactivities with C1q and fibronectin have to be taken into account.
Since type II collagen is the predominant cartilage collagen and since type II collagen can induce an experimental arthritis in mice and rats, autoimmunity to type II collagen is of special interest in RA. However, their determination is curently more important for scientific than for diagnostic purposes.