Antibodies to histamine. Specificity studies and radioimmunological assay

Quantitative Determination of Histamine in Tears during Conjunctivitis by a Novel HPLC Method

The histamine content of tears of healthy sex- and age-matched subjects and patients affected by allergic or nonallergic inflammatory ocular diseases was determined through a new competitive reverse-phase high-performance liquid chromatography (HPLC) method. Tear samples from 50 healthy subjects, 30 patients affected by seasonal allergic conjunctivitis, 12 patients with bacterial conjunctivitis associated with Haemophilus influenzae and 8 patients with bacterial conjunctivitis associated with Streptococcus pneumoniae were analyzed for histamine concentration by O-phthaldialdehyde precolumn derivatization-based HPLC. In physiological conditions, the tear histamine content was low (2.26 ng/ml) and did not vary in relation to age and sex. Histamine levels were significantly higher in all the patients studied, to a greater extent in those affected by allergic (23.61 ng/ml) or Haemophilus influenzae-associated (21.53 ng/ml) conjunctivitis.

Comparison of ELISA and HPLC for the determination of histamine in cheese

A competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for histamine in cheese was compared with a reversed-phase liquid chromatography (RP-HPLC) method. Cheese was homogenized with phosphate-buffered saline (PBS), centrifuged, and filtered, and the supernatant was diluted with PBS for CD-ELISA. For RP-HPLC, biogenic amines (histamine, tyramine, putrescine, and cadaverine) were derivatized with 9-fluorenylmethylchloroformate, followed by reversed-phase chromatography and fluorescence detection. Detection limits and mean recoveries (10-1000 mg/kg) were 2 mg/kg and 93% for CD-ELISA and 1 mg/kg and 99% for RP-HPLC, respectively. Analysis of 50 commercial cheeses according to both methods showed good agreement for histamine (r = 0.979; concentration range = 2-1800 mg/kg). At a threshold level of 10 mg/kg, the ELISA gave no false-negative and three false-positive results. The results show that the ELISA is suitable for the determination of histamine in cheese.

Production of monoclonal antibody against histamine and its application to immunohistochemical study in the stomach

A monoclonal antibody against histamine has been produced. A histamine-haemocyanin conjugate prepared using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling agent was used for immunizing mice. Immunized mice were sacrificed to prepare monoclonal antibody using a hybridoma technique. On immunospot assay, the hybridoma culture supernatant containing a monoclonal antibody was capable of detecting 50 pmol of histamine. Using this antibody, we examined the cellular localization of histamine-like immunoreactivity in the stomach of normal or alpha-fluoromethylhistidine-treated rats and mice. Immunoreactive cells were abundant in the gastric mucosal layer. These positive cells were often located in the basal half of the fundic gland but were rare in the pyloric gland. The cells, small or medium in size, spindle or cone in shape, were intermingled with immunonegative epithelial cells. In the cytoplasm of the positive cells, granular reaction products were densely deposited. In addition, a few positive cells, identified as mast cells by Toluidine Blue staining, were distributed mainly in the submucosal and muscular layer. The antibody preabsorbed with 10 mM histamine gave no positive immunostaining. For pharmacological study, some rats were injected six times with c-fluoromethylhistidine every 8 h. In these rats, positive cells except mast cells were no longer detected. In conclusion, the monoclonal antibody produced appears to be highly specific for histamine. Its application in immunohistochemistry should provide a powerful tool for analysing the roles of histamine in enterochromaffin-like or mast cells in the stomach.

Histamine measurement in whole blood and cell supernatants. A comparative study of two different radioimmunoassays

Histamine as an important mediator of the allergic reaction has been measured by a number of methods both in whole blood and cell supernatants after in vitro release. We compared the fluorometric histamine assay with two radioimmunoassays and studied detection limit, recovery, cross-reactivity and accuracy in buffer-based standards as well as the sensitivity after IgE-mediated in vitro release from washed cells and whole blood. Our data indicate that the double-antibody RIA (Pharmacia) can be used for studies of basophil histamine release in both whole blood and cell supernatants. Due to significant cross-reactivity to N-methyl-histamine it cannot be used for histamine determinations in plasma. The second radioimmunoassay using succinyl-glycine as an acylating reagent and monoclonal antibodies, which have been raised to acylated histamine, is the most sensitive assay without any cross-reactivity with methylhistamine.

Recognition of imidazole and histamine derivatives by monoclonal antibodies

The different ways of raising antibodies to histamine are reviewed. High affinity monoclonal antibodies could be raised only against derivatized histamine. Succinyl glycinamide derivatization provided the basis of an efficient radioimmunoassay. In this paper the molecular pattern and the thermodynamical properties of histamine recognition were thoroughly investigated. Only the neutral form and not the cationic form of imidazole was recognized. As expected, the ligand recognition increased, with improved structural homology to the immunogen. However, a detailed analysis revealed a zwitterionic effect whenever a carboxylic group was present on the side chain of the ligand.

An immunoenzymoassay for histamine

The clinical diagnosis of allergies needs appropriate tools for the measurement of histamine release from leukocyte suspension of affected patients. In the last few years the established fluorometric procedure has been challenged by alternatives like histamine radioimmunoassays (RIA). Although measurements of histamine with the latter methods make this procedure more accessible as a diagnostic tool, further simplifications are always welcomed. A newly developed immunoenzymoassay for histamine is described in the present work and compared to a recent radioimmunoassay. Sensitivity and specificity are shown to be comparable in both procedures.

An immunoassay for histamine based on monoclonal antibodies

Monoclonal antibodies with high specificity for histamine as well as for 1-methylhistamine were obtained after immunization of mice with a conjugate where the histamine was coupled via its ring 1-nitrogen to dog serum albumin. An immunoassay was developed for the quantitation of histamine release from basophils and 1-methylhistamine release from mast cells after provocation. The test method is based on competitive inhibition between histamine and a labelled histamine conjugate for the antigen binding sites of the antibodies. The separation step is performed by the addition of solid phase bound anti-mouse subclass specific antibodies. The sensitivity of the assay is 2 micrograms/l for histamine and 0.1 micrograms/l for 1-methylhistamine. No cross-reactivity was obtained with other metabolites of histamine or with histidine. Serotonin and dopamine were detectable, but only in doses (mg/l) well above the normal concentration found in the circulation. The immunoassay has been evaluated for its capacity to measure histamine release in vitro. A good correlation with the conventional fluorometric assay was obtained when histamine released from allergen stimulated leucocytes from allergic patients was tested. Urinary samples from patients undergoing hyposensitization showed a mean excretion of 1-methylhistamine at a level of 131 mumol MeHi/mol creatinine. The release of histamine and 1-methylhistamine in vivo was examined in plasma samples taken during a bronchial provocation test. A significant elevation above the basal analyte level occurred ten minutes after provocation.

Evaluation of a radioimmunoassay for histamine measurement in biologic fluids

A new radioimmunoassay for the measurement of histamine in biologic fluids was evaluated. Assay selectivity and specificity were achieved by "succinyl-glycinamide derivatization" of histamine in samples to mimic the immunogen used to generate the monoclonal antibody. The assay exhibits a linear response from 0.1 to 5.0 ng/ml of histamine and the monoclonal antibody used has partial recognition of only N-methylhistamine (other than histamine). With minimal modifications, the assay can accurately measure histamine in plasma, urine, and buffer. Normal ranges for human subjects were established: plasma levels are 0.193 +/- 0.08 ng/ml (n = 40) and urine levels are 20.9 +/- 11.2 micrograms histamine/gm creatinine (n = 10).