Passive cutaneous anaphylaxis induced in guinea pigs by insulins and their component chains

Small amounts of purified ox insulin and its component chains provoked passive cutaneous anaphylaxis (PCA) in guinea pigs previously injected intradermally with antiserum to ox insulin. Cod insulin and its chains also yielded a PCA reaction with antiserum to cod insulin, indicating that antibody-combining sites are located on both the A- and B-chains of insulin Enzymic digestion of the chain preparations essentially destroyed their ability to combine with anaphylactic antibodies, although the B-chain digests had some residual PCA reactivity.Ox and cod insulins gave positive PCA reactions with the heterologous antiserum but at higher levels than with the homologous antiserum, and none of the four chain preparations reacted with the heterologous antiserum. These results demonstrated differences between the antibody-combining sites on the chains of ox and cod insulins.Insulins from a wide range of species also yielded a PCA reaction with antisera to cod and ox insulins, suggesting that the different hormone preparations have certain antigenic determinants in common. Immunologic relationships between several insulins were derived from the competitive inhibition of one antiserum by the other when both were present in the same animal.

Starfish insulin

Acid–isopropanol extraction of digestive tissue from the starfish (Pisaster ochraceous) yielded material with properties resembling those of insulins from vertebrate species. The starfish extract enhanced glycogen deposition in mouse diaphragm tissue, with a dose–response slope similar to that of crystalline insulin from the ox; this specific effect of the starfish material was significantly reduced by a large excess of guinea pig antiserum to ox insulin, proving that the active starfish substance was insulin. The crude starfish insulin was similar to ox insulin in sensitivity to mercaptoethanol and was able to provoke cutaneous anaphylaxis in guinea pigs passively immunized with antiserum to ox insulin. Pseudoisocyanine-stained sections of starfish digestive tissue revealed metachromatic granules similar to those seen in mammalian β-cells.