Insulin-binding antibody: Reaction differences with bovine and porcine insulins

Insulin treated patients frequently develop insulin-binding antibody. Antisera from some patients, treated with bovine or bovine/porcine insulin mixtures, react differently with bovine and porcine insulin while for others there is no difference: when there is a difference there is greater avidity for bovine than porcine insulin. We studied antisera from 16 patients who had previously been treated with bovine insulin and then were changed to porcine insulin. Dissociation rate constants and association rates were measured with bovine and porcine insulin. Significant differences were found in association rates, which correlated well with binding at equilibrium (r=0.91), but not in dissociation rates. For 11 subjects who stayed on highly purified porcine insulin, long term reduction in insulin requirement correlated with the magnitude of the difference in antibody reaction to bovine and porcine insulin (r=0.74).