Molecular mimicry of human tumor antigen by heavy chain CDR3 sequence of the anti-idiotypic antibody

We isolated and characterized an anti-idiotype monoclonal antibody (ARA42.1 ) which is capable of mimicking a distinct and specific epitope of MUC-1 an tigen. The cDNA sequences coding for the AR42.1 variable regions were deter mined, We found significant amino acid homology between complementary deter mining regions 3 (CDR3) in the heavy chain of AR42.1 and the determinant ep itope sequence of MUC-1. This 10 amino acid sequence may represent an "inte rnal image" of the anti-idiotype antibody to the MUG-I antigen, and could b e used for development of a MUC-1 surrogate for immunotherapy.