Interactions between the immune system and connective tissue in arthritis. Possible significance of an affinity between IgG and native type II collagen.

Abstract

The synovial inflammation in rheumatoid arthritis (RA) resembles inflammatory reactions in other tissues concerning features such as increased expression of MHC class II antigens and infiltration of large amounts of activated T lymphocytes. The present communication is concerned with how to explain features such as local production of rheumatoid factors that distinguish the synovial inflammation in seropositive RA from other chronic inflammatory reactions; We show here that monomeric IgG and, to an even higher extent, aggregated IgG show a high binding capacity for native collagen type II. This finding is discussed in the light of previous findings that native collagen II structures are readily exposed to the environment in the cartilage of inflamed joints, and the evidence that T-cell reactivity to cartilage-derived molecules among them collagen II appears to be a common feature in seropositive RA. We suggest that an enhanced formation of IgG-collagen II complexes in RA joints, together with activation of T-cells to collagen II or collagen II-associated structures may constitute the basis for local rheumatoid factor production and to disease perpetuation in seropositive RA.