Preparation of specific antibodies to catecholamines and L3,4-dihydroxyphenylalanine. III. Preparation of antibody to epinephrine for radioimmunoassay

Plasma catecholamines: laboratory aspects

In this review the methods used for analysis of plasma catecholamines in clinical chemical laboratories are discussed. The physiology of catecholamines as well as their measuring indications are discussed, together with concise evaluation of the methods most commonly used, namely indirect radioenzymatic assays or direct determinations by high-performance liquid chromatography combined with either electrochemical or fluorometric detection. The main advantage of radioenzymatic assay is its sensitivity and thus the need for only a small sample. Liquid chromatographic methods in general are less tedious, relatively rapid, and cheap, and omit the use of radionuclides. Both of these methods, however, are subject to a number of analytical errors, which can only be avoided by proper development of methods and skilled use of these methods. Little routine work is done using either radioimmunoassay or gas-chromatography.

Antibodies to dopamine: radioimmunological study of specificity in relation to immunocytochemistry

Two classes of anti-3,4- dihydroxyphenylethylamine (dopamine) antibodies were raised in rabbits using dopamine conjugated to albumin either via formaldehyde or via glutaraldehyde. Each was usable for immunohistochemical detection of dopamine neurons provided that the tissue was fixed by the homologous cross-linking agent. However, anti-dopamine-glutaraldehyde antibodies turned out to be of more general use because of the better fixative properties of glutaraldehyde which fixed dopamine in rat and in teleost, whereas formaldehyde only worked in lower vertebrates (such as goldfish) and not in rat brain. The specificity of anti-dopamine-glutaraldehyde antibodies was firmly established by competition experiments in equilibrium dialysis, using an immunoreactive tritiated derivative synthesized by coupling dopamine to N-alpha-acetyl-L-lysine N-methylamide via glutaraldehyde. Specificity studies in vitro and immunohistological results demonstrating the specific staining of dopaminergic neurons were found to correlate well.

Antisera against catecholamines: specificity studies and physicochemical data for anti-dopamine and anti-p-tyramine antibodies

Antibodies against dopamine and p-tyramine were raised in rabbits. The two catecholamines were conjugated to albumin by glutaraldehyde. The specificity of the antibodies was established by equilibrium dialysis competition experiments using an immunoreactive tritiated derivative synthesized by coupling dopamine or p-tyramine to N-alpha-acetyl-L-lysine N-methylamide with glutaraldehyde. Hence, these radiolabelled ligands mimicked the antigenic determinant of conjugated immunogens. A comparison of the data obtained showed the high specificity of each antiserum for its hapten coupled by glutaraldehyde. The anti-dopamine antibodies recognized dopamine-glutaraldehyde but not p-tyramine-glutaraldehyde. The opposite occurred for the anti-p-tyramine antibodies. A slight modification of the molecular structure provided the opportunity for a specific response against that molecule. But this difference was more important when related to the hapten region where the antibody affinity was maximal. The cross-reactivity was observed to be more important dopamine and p-tyramine than between dopamine and noradrenaline on the one hand and between p-tyramine and dopamine than p-tyramine and octopamine on the other hand.

Preparation of antibodies to catecholamines and metabolites--syntheses of various immunogens and characterization of the resulting antibodies

The synthesis of antigens of the haptens p-tyramine, octopamine, synephrine, dopamine, normetanephrine, beta-(3,4-dichlorophenyl)-ethylamine and 3-fluoro-tyramine is described. The coupling of the haptens to the carrier protein was performed either via the side chain by means of succinic anhydride, or through the phenolic ring via an aminomethyl group which was introduced by a Mannich reaction. Antisera to these haptens were produced in rabbits by immunization with these antigens. The antisera were characterized by determination of titer and specificity (p-tyramine, synephrine, normetanephrine). The possibility is discussed of using antisera to p-hydroxyphenylethylamine for a radioimmunological determination of catecholamines.