Monoclonal 'internal image' anti-idiotypic antibodies of hepatitis B surface antigen.

The hypervariable regions of the immunoglobulin molecule which function as the antigen-combining site are, themselves, capable of provoking an antibody response. These antigenic determinants on the immunoglobulin are termed the 'idiotype', and antibodies directed against them 'anti-idiotype'. In circumstances where there is a close complementarity of shape between antigen and idiotype, and subsequently between idiotype and anti-idiotype, it would be predicted that anti-idiotype would be like an 'internal image' of the antigen. Starting with a monoclonal antibody (idiotype) to the protective a determinant of the hepatitis B surface antigen (HBsAg), we have succeeded in raising two monoclonal anti-idiotypes which mimic HBsAg in their ability to bind polyclonal antibodies to HBsAg produced in a variety of species. These internal image anti-idiotypes may provide a strategy for immunization without the need for antigen.