THE SIGNIFICANCE OF THE NUMBER OF PRECIPITIN BANDS IN AGAR GEL MEDIUM FOR THE DETERMINATION OF THE COMPLEXITY OF ANTIGENS

Abstract

A new interpretation is presented to account for inconsistancies which may arise when comparing data obtained with antibody–antigen systems in agar and in liquid media. For a model system, different haptens (p-aminobenzoic acid and p-sulphanilic acid) coupled to proteins were used. It has been demonstrated that the number of precipitin bands formed in agar medium by these antibody–antigen systems may be smaller than the number of optimal proportion zones detected for these systems in liquid medium, provided the different haptens are coupled to the same carrier. This effect is not due to a lesser sensitivity of the reaction in agar but rather to the inherent limitations of this method. Thus, by the agar technique, not more than one antigenic moiety (present on a molecule) is detected, whereas by the precipitin test in liquid medium optimal proportion zones with respect to each of the antigenic moieties (on the molecule) may be detected. This limitation in agar is not considered to detract from the value of the agar gel technique when it is used for the detection of independent antigens.