A sensitive radioimmunoassay for adenosine in biological samples

A simple, sensitive, specific, and reproducible radioimmunoassay for the measurement of adenosine in biological materials has been developed. Adenosine antibody was obtained by immunizing rabbits with an immunogen prepared by conjugating 2′,3′-disuccinyladenosine to human serum albumin. By succinylating adenosine in samples at the 2′- and 3′-O positions with a premixed reagent consisting of succinic anhydride, triethylamine, and dioxane, the assay became sensitive enough to detect less than picomole amounts of adenosine in minute quantities of tissues. The corss-reactivity of structurally related compounds with the antibody was mostly negligible except for 2′-deoxyadenosine, whose usual concentration was very low. The use of this method made it possible to measure adenosine without any prior purification procedure. The immunoreactive materials in various biological samples disappeared during incubation of the samples with adenosine deaminase.