Anti-idiotypic antibody (anti-ID antibody) is a class of antibody that specifically binds to the antigen-binding site of an antibody. For each antibody molecule, the region that makes contact with an antigen is called complementary determining region (CDR) which is a unique site to be found within the variable (V) regions of an antibody heavy chain and light chain.https://www.creativebiolabs.net/anti-idiotypic-antibody_71.htm