Collagen-induced arthritis is mediated by autoantibodies to type II collagen (CII). This experimental model has proven useful in determining the molecular and cellular mechanisms responsible for autoimmune arthritis. We have shown that polyarthritis can be transferred to normal mice by administering combinations of three or four complement-fixing monoclonal antibodies (mAbs) which recognize cross-reactive epitopes on the alpha 1(II)-CB11 region of chick and mouse CII. Currently, the light- and heavy-chain variable-region structures on a panel of alpha 1 (II)-CB11-specific mAbs that cross-react with chick and mouse CII, or react solely with chick CII, have been analyzed. The results indicate biased usage of VK19 and VK21 families of light-chain variable-region genes but random VH gene usage. Interestingly, two mAbs derived from different mice recognized identical epitopes on mouse CII and had nearly identical light- and heavy-chain variable-region structure including junctionally derived sequence.