Antigenic determinant definition

Definition of the association (or avidity) constant for such multivalent antibody—antigen reactions must consider not only the heterogeneity of the antibodies and the antigen determinant site(s), but also an apparent additive effect of binding two antigen molecules to a single antibody. Such effects lead... 

Problems may also arise with respect to specificity when ELISAs are applied for trace residue analysis, because any compound whose molecule is in part identical with or closely similar to the antigenic determinant of the analyte can compete for antibody-binding sites. Therefore, immunochemical methods are valuable for screening and testing purposes but cannot be considered as definitive from a regulatory perspective. For legal enforcement use, these methods should be used as part of an analytical system that consists of additional methods capable of definitively identifying the compounds of interest. 

Feizi, T., E.F. Hounsell, J. Alais, A. Veyrieres, and S. David. 1992. Further definition of the size of the blood group-I antigenic determinant using a chemically synthesised octasaccharide of poly-N-acetyllactosamine type. Carbohyd. Res. 10 289-297. 

---