idiotype

https://doi.org/10.1351/goldbook.13252
The combined antigenic determinants (idiotopes) expressed in the variable (V) region of immunoglobulins (Ig) of an individual that determine antibody specificity to a particular antigen.
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1182 [Terms] [Paper]