A lone antibody can unravel collagen fibers, possibly contributing to the destruction of cartilage in people with rheumatoid arthritis.
Picking apart proteins was thought to be a job reserved for enzymes and immune cells. But an antibody that attacks a protein called biglycan can cause bundles of collagen fibers to fray like the ends of a string of yarn, Joseph Orgel and Olga Antipova of the Illinois Institute of Technology in Chicago report online March 13 in PLoS ONE. And the antibody works alone, with no help from destructive cells or enzymes, the researchers found.
Rheumatoid arthritis is a disease in which the immune system attacks and destroys the cartilage — which is composed mainly of collagen — that cushions joints. Previous research has shown that patients with the disease have high levels of the biglycan-attacking antibody in the fluid that lubricates joints. Antibodies are known to guide immune cells to destroy invading microbes or dangerous proteins, but not — until now — to do demolition work on their own.