Limited Heterogeneity of Antibodies against the Para-Azobenzoate (Xp) Hapten

Abstract

A series of IgG antibodies raised in 21 rabbits against the p-azobenzoate hapten was examined by isoelectric focusing in acrylamide gels. Specifically purified antibodies from 14 of the rabbits gave isoelectric spectra that consisted of only five or fewer patterns similar to those obtained from myeloma proteins, which showed a single pattern consisting of a series of three or more regularly spaced lines. A restricted number of patterns indicates limited heterogeneity. Five of the preparations were very restricted, giving primarily a single pattern. Four of these five preparations also gave a single band in isoelectric focusing of the light chains and four also appeared homogeneous with respect to binding constant. One antibody preparation that gave two simple patterns on isoelectric focusing and two light chain bands was fractionated to give a fraction with a single isoelectric focusing pattern and a single light chain band. For two rabbits the same antibody isoelectric focusing pattern persisted for over 1 year. On the basis that a simple pattern represents a biosynthetically homogeneous antibody species, a large proportion of the rabbits produced primarily one to five different antibody molecular species directed against this hapten.