Development of a sensitive radioassay of histamine for in vitro allergy testing.
A radioenzymatic assay for the measurement of histamine is described, based on the incubation of histamine in the presence of histamine-N-methyl-transferase from rat kidney and [3H-methyl]-S-adenosyl-L-methionine (sp act 15 Ci/mmol) in phosphate buffer, 0.05 mole/l, pH 7.9, at 37 degrees C for 60 min. The N-[3H]-methyl]histamine generated was selectively extracted into toluene/isoamyl alcohol (3:2) and the quantity of the tritium in the sample was determined by liquid- scintillation counting. As little as 1 nmol/l of histamine can be detected. The assay is specific, with no cross-reactivity noted for several compounds closely related to histamine. The assay was used to measure the released histamine of a group of allergic subjects following the incubation of their blood with various allergens. A good correlation was found between histamine release from whole blood and the response of skin mast cells to intradermal antigen administration.
D000485:Allergens; D000818:Animals; D001921:Brain / Q000201:enzymology; D006168:Guinea Pigs; D006632:Histamine / Q000032:analysis* / Q000097:blood; D006637:Histamine N-Methyltransferase; D006636:Histamine Release; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006967:Hypersensitivity / Q000175:diagnosis*; D007668:Kidney / Q000201:enzymology; D051381:Rats; D012436:S-Adenosylmethionine; D012882:Skin Tests; D014316:Tritium
D000485:Allergens; D014316:Tritium; D012436:S-Adenosylmethionine; D006632:Histamine; D006637:Histamine N-Methyltransferase