Stimulation of antiglucagon antibodies in rabbits and guinea pigs using a glucagon-carbodiimide-albumin conjugate.

Rabbits and guinea pigs were immunized monthly with a glucagon-bovine plasma albumin conjugate prepared at a molar ratio of 12: 1 using 1-ethyl-3(3-dimethyl-aminopropyl)-carbodiimide as the coupling agent. The animals were bled regularly two weeks after inoculation and the resulting glucagon antisera analyzed for titre, affinity and specificity. Immunization of rabbits resulted in the production of large amounts of high affinity glucagon antibodies which in two out of five animals reacted between 3 and 7% with GLI (glucagon-like immunoreactivity). Antibody titre and affinity rose rapidly in the majority of rabbits attaining near maximal values by 10 weeks. In comparison, the conjugate displayed enhanced immunogenicity in the guinea pig, and antibody titre and affinity which were already several fold higher at 10 weeks continued to rise progressively during the 26 week period of immunization. Antisera raised in guinea pigs reacted particularly strongly with GLI, and antibodies derived from one particular animal yielded practically identical dilution curves with glucagon and GLI. The present study clearly demonstrates the potential of the glucagon-carbodiimide-albumin conjugate for the production of valuable glucagon antisera in rabbits and guinea pigs. Such antisera are eminently suitable for radioimmunoassay and metabolic studies. Furthermore, it is concluded that the guinea pig is a particularly useful species for the rapid production of very high quality cross-reacting glucagon antisera.