Antibody heterogeneity: theoretical and experimental evaluation of a simple procedure to describe differing...

Heterogeneity in antibody binding affinity for hapten is easily and comprehensibly described by plotting the histogram of delta r, the change in the fraction of occupied active sites, vs the logarithm of the concn of free ligand. Computer simulations of binding reactions revealed that multimodal histograms occur only if differences in affinity are greater than 10-fold. Otherwise, the delta r histogram closely approximates a normal distribution, the variance of which increases with increasing heterogeneity. In biochemical experiments delta r histograms successfully detected mixtures of anti-DNP antibodies of varying affinities as well as changes between early and late anti-DNP immune responses in rabbits immunized with or without Freund's complete adjuvant.