Antigenic Determinants: Isotype, Allotype and Idiotype

An antibody of one person can act as an antigen in another person's body
Thi There are specific regions on antibodies that can induce the immune system to produce antibodies against them

This possible due to antigenic determinant sites present in an Immunoglobulins

These are of three categories
1. Isotype : Lies in constant region of heavy chains, gives rise to class and subclass in Igs

2. Alotype:

Idiotypic determinants are generated by the conformation of the amino acid sequences of the heavy- and light-chain variable regions specific for each antigen. Each individual determinant is called an idiotope, and the sum of the individual idiotopes is the idiotype These differences are inherited and are due to different alleles. They produce subtle differences in amino acid sequence

One person can have only one ALLOTYPE

These subtle differences are seen in IgG, Ig A2 and Kappa region of constant Light Chain

3. Idiotype: Idiotypic determinants are generated by the conformation of the amino acid sequences of the heavy- and light-chain variable regions specific for each antigen.

Each individual determinant is called an idiotope, and the sum of the individual idiotopes is the idiotype These are due to differences in Variable region of both light and heavy chain

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