Idiotypic analysis of human anticentromere autoantibodies

The idiotypes (Ids) of anticentromere antibodies (ACA) have been studied using a fusion protein obtained from cloned cDNA of the major centromere antigen, CENP-B, for isolation of the autoantibodies. IgG-ACA were affinity purified from 4 patient sera and anti-Ids prepared in rabbits. Analysis revealed the existence of two distinct types of immunodominant Ids. One Id is near the antibody combining site and one is framework associated. A longterm longitudinal study of Id expression in a patient who seroconverted from ACA (-) to ACA (+) when she developed Raynaud's phenomenon showed a close correlation between Id expression and ACA titers (r = 0.94). These results may be interpreted as evidence for an autoantigen driven process in the anticentromere immune response.