Origin of the autoreactive anti-type II collagen response. II. Specificities, antibody isotypes and usage of V gene families of anti-type II collagen B cells.

Autoantibodies play an important role in the pathogenesis of type II collagen-induced arthritis in mice. We have earlier reported a high frequency of cells producing anti-CII autoantibodies and a low frequency of cells producing multispecific antibodies, in regional lymph nodes 9 to 11 days after primary immunization with CII. It is shown here that anti-CII antibodies produced during primary immune response are IgG-antibodies mainly of IgG2a, IgG1 and IgG2b subclasses while IgM antibodies dominate primary responses elicited by OVA and denatured CII as analyzed with a large panel of hybridomas. Anti-CII antibodies generated during the primary response recognize at least five different epitopes on the CII molecule. The specificities of these antibodies for various epitopes result from combinational association of products encoded by genes derived from various VH and VK families and/or by the occurrence of somatic mutations. It is suggested that the primary anti-CII autoantibody response involves activation of memory B cells and is in this aspect different from the origin of "natural" autoantibodies.