[Radioimmunological aspects of neuropeptides]

Immunological aspects of neurosecretory peptides are relevant to antibody generation, labelling of peptides for radioimmunoassays and in particular the metabolism of neuropeptides. Antibodies were generally produced by adsorption or polymerization (using different approaches and various coupling agents) of peptides with intrinsic antigenic molecules preceding their administration to recepient animals (rats, guinea pigs, rabbits and sheep) with adjuvants. Antibodies were also obtained by injecting peptides alone with or without adjuvants. However, independent of the recipient species, the highest specific or nonspecific antibody titers were obtained by the former method. Up to now, only 3H-peptides or 125I-peptides or derivatives were used as tracers in RIAs. Highest sensitivities were generally obtained when using 125I-peptides. However, 125I-peptides may be adsorbed ("false titers") to some antiserum with sufficient specificity in terms of displacement by structural analogues of the peptide but with a loss of sensitivity. Finally, large molecular forms, cross-reacting with the antibodies prepared with different methods and peptidasic activities must be taken into account. These topics are presented with data on LHRH, TRH and substance P derived from our experiments and from those of other investigators.