A method for enhancing production of antibodies through immunization with insolubilized immune complexes is disclosed. Purified antigen or heterogeneous antigen mixtures may be combined with polyclonal or monoclonal antibody and the resultant complex bound to insolubilized protein A to form insolubilized immune complexes. Methods for improving the immunogenicity of a soluble antigen and for producing monoclonal anti-idiotypic antibodies are also disclosed. Monoclonal antibodies that are specific for a distinct, as yet unrecognized epitope may be produced by another disclosed method. Insolubilized immune complexes, comprising antigen and antibody that is either directly linked to Sepharose.RTM. or absorbed onto insolubolized protein A, and immunosorbents, comprising antibody absorbed onto insolubilized protein A, are also disclosed.