Glomerular structural changes in rabbits on treatment with bovine and porcine insulin. A morphometric analysis

Weak nonspecific immunological stimuli can irritate the glomerular mesangium as observed following administration of insulin preparations of varying degrees of purity. In the present study further substances were investigated with regard to this effect. We wished to examine which substances obtained during purification of insulin are mainly responsible for the antigenicity, and whether porcine and bovine MC insulin have the same antigenic properties. Rabbits were treated for up to 90 days with bovine MC insulin, bovine proinsulin, bovine a + b-component, porcine a-component and porcine b-component. The kidneys were analysed morphometrically and antibody titers to bovine insulin, a-component, porcine PP and proinsulin were determined in the various test groups. It was found that bovine MC insulin and porcine MC insulin possess the same immunological activity, i.e. no antibody formation to either of the two insulins was demonstrable. Similarly, there were no differences in the morphometric findings; slight transient mesangial changes were demonstrable after both insulins. However a-component and b-component showed a pronounced immunogenic potency with antibody formation. Marked and partly persisting mesangial alterations were demonstrable, with the antigenicity of the a-component being particularly marked. The implication of the study is that a "pure" or optimally purified insulin should be used in the therapy of diabetes mellitus.