The B cell response to autologous type II collagen: biased V gene repertoire with V gene sharing and epitope shift.

Collagen-induced arthritis is an autoimmune model disease induced in the DBA/1 mouse immunized with type II collagen (CII). Both T and B cells play a critical role for the induction of arthritis. Draining lymph nodes from CII-immunized mice contain high numbers of CII-specific B cells, which are isotype switched and V gene selected. In the present study we analyze the V region gene usage and epitope specificity of CII-reactive B cell hybridomas, randomly isolated from the primary and the secondary response in mice immunized with rat CII we make the following conclusions. 1) There are major epitopes in the native CII molecule to which the B cells preferentially respond. 2) B cells specific for the same epitope show a preferential pairing of certain VH/VK genes or a biased usage of individual VH (VHJ558 and VHX24) or VK genes (VK21). 3) The V genes are germ line encoded in the primary response and somatically mutated in the secondary response. Somatic mutations give the Abs cross-reactivity between CII epitopes, and epitope shift, i.e., another epitope within the CII molecule is recognized. 4) There is a sharing of certain V genes in B cell clones specific for different epitopes, indicating structural similarities of the different CII epitopes.