The dissociation of insulin from human insulin antibodies

The dissociation of insulin from human insulin antibodies has been investigated using a technique that is rapid and does not require addition of excess unlabelled insulin. A slow (k₁ = 2·1^?3 min^?1 and a fast (k₂ = 4·10^?2 min^?1) dissociating antibody component were identified in all studies. These have been shown to correspond, respectively, to the high and low affinity antibody components of equilibrium binding studies. The range of k₁ and k₂ values and their response to temperature change is small. Insulin resistance and stability of diabetes are not related to properties of antibody dissociation. Dissociation is faster in the presence of high (6–850 nM) insulin concentration due to increased binding to the fast dissociating component without change in the dissociation rate constants. When incubation time is increased beyond achivement of maximal binding there is a time-dependent rise in binding to the slow dissociating component, with a concomitant fall in k₁. The traditional concept that equilibrium is established at maximum binding requires further examination.