A novel double-isotope technique for the enzymatic assay of plasma histamine: application to estimation of mast cell activation assessed by antigen challenge in asthmatics

Journal Article · Fri Jan 01 04:00:00 EST 1982 · J. Allergy Clin. Immunol.; (United States)

DOI:https://doi.org/10.1016/0091-6749(82)90082-3· OSTI ID:5443015

Brown, M J; Ind, P W; Causon, R; Lee, T H

The concentration of plasma histamine may provide an index of mast cell activation (degranulation) and can be measured by a sensitive radioenzymatic assay based on its specific conversion to (/sup 3/H)-methylhistamine in the presence of histamine-N-methyltransferase and (/sup 3/H)-S-adenosyl-L-methionine. In this assay, the separation of excess (/sup 3/H)-S-adenosyl-L-methionine from (/sup 3/H)-methylhistamine requires several steps, for which a correction factors is necessary to maintain precision. In the present modification, duplicate 50-microliters aliquots of each plasma sample were incubated with histamine-N-methyltransferase and (/sup 3/H)-S-adenosyl-L-methionine. A further aliquot, with an added standard of 200 ng/ml histamine, was incubated with histamine-N-methyl-transferase and (/sup 14/C)-S-adenosyl-L-methionine. This standard was converted to (/sup 14/C)-methylhistamine, and its recovery at the end of the assay corrected both for varying efficiency of methylation among plasma samples and for losses during the subsequent extraction and separation stages. The sensitivity of the assay was 25 pg/ml. The intra-assay and interassay coefficients of variation were 7.2% and 11.6%, respectively. In five asthmatics, antigen challenge caused a 28% fall in FEV1, and this was associated with a twofold to threefold rise in plasma histamine concentration. This assay may thus prove a useful method for assessing the role of mast cell release of mediators in vivo.

• Research Organization: Department of Clinical Pharmacology, Royal Postgraduate Medical School, London, U.K
• OSTI ID: 5443015
• Journal Information: J. Allergy Clin. Immunol.; (United States), Journal Name: J. Allergy Clin. Immunol.; (United States) Vol. 69:1 Pt 1; ISSN JACIB
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINES
AMINO ACIDS
ANIMAL CELLS
ASTHMA
AZOLES
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CONNECTIVE TISSUE CELLS
DISEASES
DRUGS
DUAL-ISOTOPE SUBTRACTION TECHNIQUE
ENZYMES
HETEROCYCLIC COMPOUNDS
HISTAMINE
IMIDAZOLES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPOTROPIC FACTORS
MAST CELLS
METHIONINE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PATHOLOGY
RADIOASSAY
RESPIRATORY SYSTEM DISEASES
SENSITIVITY
SOMATIC CELLS
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS