Production and Characterization of Specific Antibodies to Bombesin

In order to produce a specific bombesin antiserum far very sensitive radioimmunoassay, synthetic $[lys^3]-bombesin$ conjugated to bovine serum albumin was subcutaneously injected into guinea pigs. The conjugation was performed using either carbodiimide or gIutaraldehyde as a coupling agent. The antisera were characterized by analysis of Scatchard and Sips plots. The antiserum LBE 2G/2 raised by repeat injection of the immunogen conjugated with carbodiimide showed the titer of 1 : 188,000, very low cross-reactivity to bombesin-like peptides except bombesin, with high affinity constant $(1.64{\times}10^{11}\;M^{-1})$ and high heterogeneity index (0.91). The antiserum LBG 1G/2 produced by repeat injection of the immunogen conjugated with glutaraldehyde possessed the titer of 1 : 43,000, high cross-reactivity to some bombesin-like peptides, high affinity constant $(1.19{\times}10^{11}\;M^{-1})$ and high heterogeneity index (0.79). These results indicate that the antiserum LBE 2G/2 is specific only to bombesin and that the antiserum LBG IG/2 binds to some bombesin-like peptides such as alytesin, gastrin releasing peptide and neuromedin C. The antiserum LBE 2G/2 is sufficient for the very sensitive radioimmunoassay of bombesin.