Anti-idiotypic antibody as a mirror image of the paratope of the original antibody.

Immunization with 2,4-dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH) produced antibodies with combining sites (paratope) which could accommodate not only the 2,4,6-trinitrophenyl (TNP) antigen but also the 4-hydroxy-3-nitrophenyl (NP) and 4-hydroxy-5-iodo-3-nitrophenyl (NIP) antigens, while immunization with NIP-KLH or TNP-KLH produced antibodies with combining sites which could accommodate only the homologous antigens. Utilizing these cross-reacting anti-hapten antibodies mentioned above, an anti-idiotypic antibody was investigated and characterized. Anti-DNP antibodies (Ab1) cross-reacted with the epitopes TNP, NP or NIP. It was also shown that heterologous anti-anti-DNP antibodies (Ab2) recognized not only the antibody which was produced by immunization with DNP-KLH, but also the antibodies produced by immunization with NIP-KLH, NP-KLH or TNP-KLH. The guinea pig anti-idiotypic antibody which we obtained using murine anti-DNP antibodies (Ab1) as antigen is therefore better defined not as an internal image of the antigen but as a mirror image of the paratope of the immunizing Ab1.