Abstract
Antibodies to substance P (SP) produced in rabbits have been characterized for their specificity toward SP and some 30 SP-related peptides. For each compound, we observed a close correlation between capacity of binding to anti-SP antibodies and biological activity, namely their spasmogenic effect on guinea pig ileum in vitro and their hypotensive effect in the rat in vivo, indicating that the combining sites of anti-SP and SP receptor(s) are structurally very similar. Further immunization of five rabbits with anti-SP immunoglobulins elicited in two allotype-matched animals the production of anti-SP anti-idiotypic antibodies. These latter antibodies were found to strongly inhibit the spasmogenic action of SP on the guinea pig ileum. In contrast, they specifically enhanced, like SP, phospholipid turnover in rat parotid gland cells, a physiological function mediated through an activation of SP receptors. Immunocytochemical studies actually revealed the presence of specific membranous binding sites for anti-idiotypic antibodies on the parotid gland-dissociated cells. The anti-idiotypic antibodies described here, which thus behave either as agonists or antagonists for SP depending on the biological test, might be used as original and powerful tools not only in studies of the receptor stereospecificity but also in attempts to purify the membranous SP receptors.
Highlights
Antibodies to substance P (SP) produced in rabbits more than 50 years after the first descriptionof have been characterized for their specificity toward a pharmacological effect of substance P [15], little is known
Synthetic SP was conjugated to bovine serum albumin (BSA), according to the benzoquinonemethod[51].Onehundred p1 of benzoquinone (32.4 mg) in ethanol were added to 33.5 mg of BSAdissolved in 1 ml of0.1 M phosphate buffer, pH 7.4
We looked for any binding to the cells ofIgG from the first bleedings of rabbit 183 a the presence of 10"
Summary
Depending on the biological test, might be usedas orig- combining sites These anti-idiotypic antibodies shouhldave, inal and powerfutolols in studiesof the recep- in their variable region, the molecular features of substance tor stereospecificity butalso in attempts to purify the P and should be ableto bind theSP receptors. The aim of this new and original methodology as recently reviewed [19, 49,54] is to generate anti-receptor antibodies (without prior purification of the receptor) which can interact, like conventional ligands, withthe physiological. Pain [32, 37] or in the mediation of vascular tissue reactions to noxious stimuli [33]as well as for its effects on the central nervous system, in animal behavior[20]
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