Measurement of antibodies to collagen II by inhibition of collagen fibril formation in vitro

Antibodies to type II collagen (collagen II) are pathogenic in experimental collagen-induced arthritis (CIA) and possibly also in rheumatoid arthritis (RA). Hitherto, results of assays for anti-collagen II have proven to be inconsistent. We tested whether mouse monoclonal antibodies (mAbs) to collagen 11 inhibit the natural self-assembly of soluble triple-stranded collagen H monomers to form insoluble polymeric fibrils. A spectrophotometric assay of self-assembly was based on change in absorbance at 313 run, observed over 0-60 min after neutralisation and warming of a solution of monomeric collagen II. Two mAbs to collagen 11 (CII-CI and M2.139) strongly inhibited self-assembly of collagen 11 but not collagen 1, whereas another antibody, CII-F4, and an irrelevant control mAb did not. Notably, CII-CI and M2.139, but not CII-F4, induce arthritis on passive transfer to naive mice. The arthritogenic effects of mAbs CII-CI and M2.139 in vivo, and inhibition of collagen 11 self-assembly in vitro, may be attributable to interference with critical epitopes at sites essential for the stabilisation of the mature polymeric collagen 11 fibril, and, hence, the integrity of the entire cartilage matrix. This assay for inhibition, of self-assembly of collagen 11 could be developed for routine measurement of anti-collagen 11 in body fluids as a marker of early RA, and perhaps also to distinguish populations of antibodies to collagen 11 that either have or lack the capacity to perpetuate arthritis. (C) 2004 Elsevier B.V. All rights reserved.