Humoral immunity to link protein in patients with inflammatory joint disease, osteoarthritis, and in non-arthritic controls.

Abstract

SUMMARY Cartilage link protein of high purity was prepared and used in an enzyme linked immunosorbent assay (ELISA). Antibodies to link protein were sought in the sera of 98 patients with rheumatic disorders; 38 with rheumatoid arthritis (RA), 29 with osteoarthritis (OA), 13 with psoriatic arthritis (PA), nine with ankylosing spondylitis (AS), nine with systemic lupus erythematosus (SLE), and in 83 healthy controls. Antibodies were detected in all groups with the following prevalences: 21/83 normals, 9/38 RA, 7/29 OA, 7/13 PA, 3/9 AS, and 4/9 SLE. No statistically significant differences existed between the groups with regard to either prevalence or mean titre of anti-link antibodies. Serum antibodies to proteoglycan link protein appear to be no more common in patients with rheumatic disorders than in healthy controls.

Cellular immunity to cartilage link protein in patients with inflammatory arthritis and non-arthritic controls.

“…27 In the present study we have shown that a greater proportion of RA patients have peripheral blood derived T cells reactive to link protein (defined as an SI of 1.5 or greater) than non-arthritic individuals. The frequency of such responses was greater still in synovial fluid derived T cells.…”

“…ANTIGENS Link protein was purified as previously described. 27 Briefly, macroscopically normal human articular cartilage obtained from patients who had undergone total hip or knee replacement was minced and extracted with 4 molll guanidine hydrochloride (GuHCl). The extract was then fractionated by associative, followed by dissociative, caesium chloride density gradient centrifugation.…”

Immunologic intervention in the pathogenesis of osteoarthritis

“…Recently, we and other investigators have identified the involvement of humoral immunity in OA, including the presence of autoantibodies against cartilage components (24, 80–82). Mollenhauer et al (81) demonstrated elevated titers of autoantibodies against chondrocyte membrane proteins, and we (22, 24) found such a response to the cartilage matrix accessory proteins cartilage intermediate layer protein and osteopontin in OA patients.…”

“…Mollenhauer et al (81) demonstrated elevated titers of autoantibodies against chondrocyte membrane proteins, and we (22, 24) found such a response to the cartilage matrix accessory proteins cartilage intermediate layer protein and osteopontin in OA patients. Austin et al (82) detected serum antibodies to proteoglycan link protein in 26% of OA patients. Other investigators have identified antibodies to collagen in synovial fluids from OA patients and from animal models of OA (3, 83, 84).…”