Nasal Challenge with Serotonin and Histamine in Normal Persons

In order to study the nasal response to serotonin, 14 normal persons, in a double-blind study, were provoked in the nose with serotonin and histamine. Itching and the number of sneezes were noted, the amount of secretion measured, and nasal airway resistance recorded by active posterior rhinomanometry. Serotonin induced significant nasal itching, sneezing and hypersecretion, similar to the effects of histamine. The effect of serotonin on nasal airway resistance, on the other hand, was slight (+ 10%) and insignificant in contrast to that of histamine in equipotent doses (+ 48%) (P less than 0.001). In conclusion, we have shown that serotonin provocation can induce a rhinitis response in the human nose. The nasal symptoms suggest an effect on sensory nerves with reflex-induced sneezing and hypersecretion, while there appears to be little direct effect on capacitance vessels. The possible role of serotonin as a mediator of rhinitis remains speculative.     

Nasal provocation with histamine in allergic rhinitis patients: clinical significance and reproducibility

In a selected group of rhinitis patients (n = 12) with an IgE-mediated allergy to house dust mites, the nasal response to insufflation of histamine chloride appeared to be related to symptom scores obtained from the patients. In contrast to the sum of the nasal airway resistances (NAR) induced by all doses of histamine, the total amount of secretion and total number of sneezes could be predicted from clinical scores. The reproducibility of the nasal provocation test was tested by comparison of the test results in two sessions with a 1-week interval. The correlation between both sessions was highest with respect to nasal secretion (r = 0.87; P less than 0.001) and the number of sneezes (r = 0.76; P = 0.004). The correlation coefficient was 0.71 (P = 0.01) when the nasal airway resistance was used in the assessment of nasal response. A good reproducibility of the nasal provocation test was also obtained using an end-point titration method and determining the concentration required to produce 0.5 ml secretion and/or five sneezes as the end-point (r = 0.76; P = 0.004). The concentration required to double nasal airway resistance yielded a correlation coefficient of 0.56 (P = 0.052). We conclude that the clinical significance of nasal provocation with histamine increases when, besides nasal airway resistance, the amount of secretion and the number of sneezes is used in the assessment of the nasal response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of the nasal provocation test for its necessity in the diagnosis of nasal allergy to house dust mite

The aim of this study was to evaluate rhinomanometric responses to nasal allergen provocation in children with allergic rhinitis sensitized to house dust mite. We studied 51 children, aged 6-16 years (mean: 11.5 +/- 2.6 years), with clinical symptoms of perennial allergic rhinitis without asthma and 20 non-atopic healthy controls in the same age range (mean: 11.8 +/- 3.8 years). All of the patients had positive skin prick test (SPT) results and serum specific IgE above 0.70 kU/l to Dermatophagoides pteronyssinus (Dp). Nasal provocation testing (NPT) was performed with increasing concentrations of Dp extracts and the nasal response was evaluated by active anterior rhinomanometry. A 100% increase of resistance in one or both nasal cavities was considered positive. There was a statistically significant difference of baseline nasal resistance (total, right and left sides) between the control and the patient groups (p < 0.001). A positive response to house dust mite allergens was recorded in 47/51 (92.2%) patients by rhinomanometry. The NPT presented no significant correlation with age, weight, height, SPT diameter, serum total and specific IgE levels to Dp and baseline nasal airway resistance values. This study suggests that a nasal provocation test with allergen is unnecessary in children with positive skin prick test and serum IgE specific to house dust mite. The rhinomanometric response to the allergen provocation does not correlate with the diameter of the skin prick test and the level of serum specific IgE.     

Stronger nasal responsiveness to cold air in individuals with rhinitis and asthma, compared with rhinitis alone

BACKGROUND: We have previously proposed that, compared with rhinitis alone, the constellation of upper and lower airway allergic disease is a manifestation of a more severe form of a syndrome affecting the entire airway. If this is correct, not only the lower, but also the upper airways of patients with asthma and rhinitis should demonstrate more abnormalities compared with patients with rhinitis alone, including higher sensitivity to irritant factors. Objective To test the hypothesis that, a previously well-studied natural nasal stimulus, cold, dry air (CDA), produces a stronger response in subjects with allergic rhinitis (AR) and asthma compared with subjects with AR alone. METHODS: We performed nasal provocation with CDA on 24 individuals with asthma and rhinitis and 17 with rhinitis alone. Prior to and after the challenge, nasal symptoms were recorded using visual analogue scales and nasal lavages were performed to determine histamine and lysozyme levels. RESULTS: The two groups reacted differently to CDA: after the challenge, patients with rhinitis and asthma reported significantly higher scores for nasal congestion, rhinorrhea and lacrimation. Also in this group, significant increases in histamine and in lysozyme levels in nasal lavage fluids were induced by CDA. In subjects with rhinitis alone, CDA failed to increase histamine or lysozyme levels above baseline. The CDA-induced change from baseline in histamine was significantly higher in the patients with rhinitis and asthma, compared with the rhinitis-only group. CONCLUSION: Patients with AR and asthma have stronger nasal responsiveness to CDA compared with patients with rhinitis alone. This observation is consistent with the notion that compared with rhinitis alone, the presence of asthma and rhinitis signifies a higher degree of functional abnormality of the entire airway.     

Nasal histamine challenge in nonallergic and allergic subjects evaluated by acoustic rhinometry

Nasal patency shows spontaneous variations but is influenced by a number of factors like exercise and allergic conditions. Nasal histamine challenge has been used to define nasal hypersensitivity. We have applied acoustic rhinometry as a new objective method to study the spontaneous variations of the nasal mucosa and its response to histamine challenge in 12 nonallergic subjects and 12 subjects with nasal allergy to pollen, but out of the pollen season. Measurements of the minimum cross-sectional area and the volume of the nasal cavities were done every 15 min for 6 h. More pronounced spontaneous variations, defined by the coefficient of variation of the measurements, were encountered in the allergic than in the nonallergic subjects, especially with regard to the minimum cross-sectional areas in the nasal cavities (P < 0.02). Allergic subjects showed increased sensitivity to histamine, as compared with nonallergic subjects, during low-concentration (0.1%) challenge (P < 0.05) and a prolonged effect of histamine challenge (P = 0.01). Antihistamine (cetirizine) had a significant effect on the histamine-induced symptoms and decrease of nasal dimensions during histamine challenge, but no significant effect on pollen-induced changes. In the allergic group, the decrease in minimum area during allergen provocation correlated with the level of specific IgE (r = 0.81; P = 0.0015).     

Nasal mucosal histamine reactivity among young students and teachers,having no or prolonged exposure to a deteriorated indoor climate

BACKGROUND: In a study performed in the spring of 1995, we found a significantly greater nasal mucosal histamine reactivity among teachers, who had worked for several years in a recently renovated moisture-damaged school, than in those in a control school. In the present study we investigated the students who begun their high-school studies at both schools in the autumn of 1995 and compared them with the teachers as regards mucosal reactivity, atopy and symptoms. METHODS: Twenty-eight teachers in the target school, 18 teachers in the control school and 45 students from each school underwent a nasal histamine provocation test and a skin-prick test. They also answered a standardized questionnaire. RESULTS: The teachers in both schools had more marked nasal mucosal histamine reactivity at the lowest provocation concentrations than the students. The histamine provocation curve of the target school teachers had consistently higher values than that of the students (P = 0.0001), but its slope and shape were similar (P = 0.15), while the slope of the provocation curve of the control school teachers was flatter. However, there was only a borderline significance in this respect compared to the students (P = 0.07). Teachers with a dry and crusty appearance of the nasal mucosa on anterior rhinoscopy reacted more strongly to histamine provocation than those without this finding (P = 0.0004). There was a significantly higher frequency of skin-prick test positivity (SPT+) among the students (P = 0.03). There were no significant differences in nasal mucosal histamine reactivity between atopic and non-atopic subjects out of pollen season. CONCLUSIONS: Teachers had a significantly greater mucosal histamine reactivity than the students, whereas the latter had a significantly higher frequency of atopy. These results are compatible with an age-related pattern of mucosal reactivity. A crusty appearance of the nasal mucosa seems to predispose to an increase in histamine reactivity. There were no significant differences according to histamine reactivity between atopic and non-atopic subjects.     

Histamine and methacholine do not increase nasal reactivity

Abstract. Allergen provocation in the nose increases the non-specific nasal reactivity. The aim of this trial was to determine whether this'priming effect' can be caused by histamine or methacholine, which is the most important biochemical mediator of allergic rhinitis, and an analogue to the important neurotransmittor, acetylcholine, respectively. Intranasal provocation tests with the two substances were carried out on thirteen normal subjects, and repeated 1 hr and 1 day later. The response, measured as the number of sneezes, the amount of blown secretion and the increase in nasal airway resistance, did not change with consecutive provocations. It was concluded that neither histamine nor methacholine were responsible for the allergen-induced'priming' of the nasal mucous membrane.     

Nasal histamine release following hyperosmolar and allergen challenge

Allergic rhinitis is characterised by symptoms of sneezing, itching of the nose with watery secretions, and nasal obstruction. We have previously shown that patients can have the diagnosis of allergic rhinitis confirmed by nasal provocation tests and assessment of nasal inspiratory peak flow (NIPF) after specific allergen or hyperosmolar challenge. We now show that histamine is released into the nasal lavage fluid in response to such challenges. Saline lavage alone results in detectable histamine levels in the order of 5 ng/ml, but in the presence of allergen (HDM) there is a significant increase in histamine release in atopics but not in control subjects. With hyperosmolar challenge, atopics showed a biphasic response in that histamine release was increased with 1.8% and 3.6% saline but returned to baseline with 5.4% and 7.2% saline, then showing a further increase with 9.0% saline. This raises the possibility of two populations of responsive mast cells. Hyperosmolar challenge leads to symptoms of nasal itch and sneezing as well as histamine release in atopics but not in controls. This suggests that hyperosmolar challenge can be used as a simple diagnostic test for allergic rhinitis and may provide a model for nasal hyper-reactivity.     

Basophil histamine release in the diagnosis of house dust mite and dander allergy of asthmatic children

The aim of the study is to compare the glass fibre-based basophil histamine release test with skin test (Phazet), RAST (Phadebas) and bronchial provocation test in children with allergic asthma. The study comprised 68 selected children with a case history of extrinsic allergic asthma to danders (cat and dog) and house-dust mite. Skin prick test, RAST, and histamine release were performed in all children and the bronchial provocation test was used as a reference of "true allergic asthma". A total of 81 allergen bronchial challenges were performed and 44 children experienced 49 positive provocations. In 2.9% (2/68) of the children histamine release could not be performed due to technical difficulties (low histamine release with anti-IgE). Concordances in the range 76-87% were observed with no significant difference between the tests. The highest concordance (87%) was found between histamine release and bronchial provocation test followed by skin prick test vs bronchial provocation (84%) and RAST vs bronchial provocation (80%). The sensitivity and specificity were calculated for each test. All tests showed sensitivities in the range 90-94% and no significant difference between them was observed. The specificity of histamine release, skin prick test, and RAST was 0.78, 0.69, and 0.63, respectively. The specificity of histamine release was better than RAST demonstrated by 95% confidence intervals. In conclusion, it was found that the histamine release test is a convenient diagnostic method and the study indicates a diagnostic value comparable to the common diagnostic methods in clinical allergy.     

Epidermal growth factor receptor - but not histamine receptor - is upregulated in seasonal allergic rhinitis

BACKGROUND: We were interested in exploring the molecular mechanisms underlying the observed difference in histamine (H) responsiveness between seasonal allergic rhinitic (SAR) and nonrhinitic (NR) subjects. We hypothesized that SAR subjects express higher nasal mucosal histamine receptor 1 (H1R) and 2 (H2R) levels than do NR subjects. In addition, we examined expression of genes involved in regulating the glandular response, including epidermal growth factor (EGF), EGF receptor (EGFR), and mucins (Muc5Ac and Muc5B). METHODS: Fourteen subjects, seven SAR and seven NR, were provoked during pollen season with doubling doses of H (0.125-8.0 mg/ml). Nasal airway resistance (NAR) was measured by active posterior rhinomanometry. Provocation was halted when NAR exceeded 150% of baseline. Prior to provocation, nasal scrapings were obtained and mRNA quantified using two-step real-time PCR. RESULTS: The mean PD50 (concentration of H producing a 50% increase in NAR) was significantly lower in the SAR than NR group (0.36 vs 1.32 mg/ml; P < 0.05). The ratio of relative gene copy numbers between the SAR and NR groups were as follows: H1R, 0.85 (P = 0.52); H2R, 0.67 (P = 0.35); EGF, 1.02 (P = 0.93), and EGFR, 103.5 (P < 0.05). CONCLUSIONS: There were no significant differences in H1R or H2R mRNA levels between SAR and NR subjects in-season, despite observed differences in H reactivity. SAR subjects, however, did show a significant elevation in EGFR expression, consistent with the observation of mucus hypersecretion in allergic rhinitis.     

Effect of salbutamol on nasal symptoms and mast cell degranulation induced by adenosine 5'' monophosphate nasal challenge

BACKGROUND: In addition to its well-known functional agonism at the level of beta(2) adrenergic receptors on airways smooth muscle cells, salbutamol appears to have additional protective effects, possibly through an inhibition of mast cell activation. OBJECTIVE: The aim of this study is to provide the first evidence in vivo of inhibition of human mast cell activation by salbutamol. METHODS: Nine atopic subjects received placebo and salbutamol (5 mg/mL) 15 min before an adenosine 5' monophosphate (AMP) nasal provocation in a double-blind crossover study design. The nasal lavage was collected from these subjects prior to or 3, 5, 15 or 30 min after the AMP nasal challenge, and concentrations of histamine and tryptase in the nasal lavage were measured. RESULTS: AMP nasal provocation produced considerable sneezing and induced a transient increase in histamine and tryptase release with peak values achieved at 3 min after the challenge in all the subjects studied. Compared with placebo, salbutamol significantly attenuated the release of histamine and tryptase induced by AMP challenge (P=0.048 and 0.020, respectively). Moreover, the AMP-induced sneezing was also inhibited by pre-treatment with salbutamol (P=0.004). CONCLUSIONS: Intranasal salbutamol attenuates nasal symptoms and inhibits histamine and tryptase release caused by AMP nasal provocation thus supporting the hypothesis that salbutamol may play an additional protective role in the airways by inhibiting mast cell activation.     

Bronchial Histamine Challenge

We compared the provocative concentration (PC) values obtained by two different methods of performing bronchial histamine challenge. One test was done on an APTA, an apparatus which allows simultaneous provocation with histamine and measurement of airway resistance (Rtot) by the interrupter method. The second test was a conventional tidal breathing method, with measurement of the FEV1. There was a high correlation between the PC20-FEV1 and the PC30-, PC40- and PC50-Rtot values. The correlation coefficients were 0.85, 0.71 and 0.70 (P less than 0.05) respectively. We further tested the reproducibility of the histamine challenge done on the APTA. When the PC30-Rtot values were compared, a correlation coefficient of 0.56 (NS) was found. For the PC40- and PC50-Rtot values the correlation coefficients were 0.65 (P less than 0.05) and 0.70 (P less than 0.02) respectively. We conclude that the APTA is useful for routine bronchial histamine challenge when 40-50% increase in basal Rtot is used as endpoint.     

Comparison of five new antihistamines (H1-receptor antagonists) in patients with allergic rhinitis using nasal provocation studies and skin tests

BACKGROUND: It was the aim of the authors to compare all of the latest second-generation antihistamines and to see if there were significant differences in their efficacy. It is important for ENT specialists to know if these differences exist, as it is for general practitioners trying to choose between these drugs. METHODS: In 12 confirmed grass pollen allergic patients the authors performed nasal smears to asses eosinophilia, histamine/grass pollen skin tests, and grass pollen nasal provocation tests. All tests were performed before and after administration of one of five different antihistamines (cetirizine, loratadine, ebastine, fexofenadine, mizolastine) or placebo. The order of administration of antihistamines and placebo was randomised, and patients were not aware of which drug they were given. A decrease in nasal eosinophilia (nasal smear), or nasal or skin reactivity (provocation tests) was looked for. RESULTS: A significant decrease in nasal eosinophilia was observed for all antihistamines but not for placebo. For the grass pollen nasal provocation tests, the decrease was significant for nasal blockage and sneezing; for rhinorrhea there was an insignificant decrease that was true for all antihistamines. A significant reduction in histamine/grass pollen skin test reactivity was also observed for all antihistamines, during an 8 h observation period. A significant difference in efficacy between the different antihistamines could not be found with any of the tests performed. CONCLUSIONS: For the newer nonsedating H1-antagonists there appears to be no clinically relevant differences in activities--at least not in our study. Preference of the patient may be the most important factor in making a choice between these drugs.     

Leukotriene C4 and histamine in early allergic reaction in the nose

We have examined the measurements of LTC4 and histamine in nasal lavage fluids and blown secretions as a possible model of the early mediator events during nasal allergy. A nasal challenge with grass pollen extract was undertaken on two separate occasions in 20 patients with a history of seasonal rhinitis and a positive immediate skin test to grass pollen. A 2 ml nasal lavage was performed before allergen challenge, and blown secretion collected separately 15 min after the provocation, followed by a final 2 ml nasal lavage. The dilution of nasal secretion by the lavage fluid was determined using 99mTc-labelled albumin as an exogenous marker added to the fluid. The amounts of admixture in the nasal lavages did not correlate to the concentrations of LTC4 and histamine, indicating that the variable amounts of nasal secretion in nasal lavage do not constitute a confounding variable for measurements of LTC4 and histamine. In the pre-challenge lavages, the median concentrations, of LTC4 and histamine were 1.7 and 52 nmol/l respectively. Following allergen challenge neither LTC4 nor histamine measured in nasal lavage showed any significant change from pre-challenge baseline values. However, measurements of both mediators in the blown secretion showed a significantly higher concentration than in the pre- or post-challenge lavage samples, compatible with transitory release during the acute allergic reaction. However, it seems doubtful whether measurements of LTC4 or histamine can be compared between blown secretion and nasal lavage fluid, even if the dilution factor is disregarded.(ABSTRACT TRUNCATED AT 250 WORDS)     

Noninvasive system for evaluating allergen-induced nasal hypersensitivity in murine allergic rhinitis

Until now there has been no method for physiologically evaluating nasal hypersensitivity in mice. Enhanced pause (Penh) has been used as an indicator that reflects changes in the lower airway. Recently, however, there is disagreement regarding the significance of the Penh system; this is because Penh is not essentially a physiological parameter, and it might not necessarily represent a change in the lower respiratory tract. The purpose of the present study is to investigate whether Penh could be applicable for analyzing nasal hypersensitivity in mice. BALB/c mice were sensitized with ovalbumin (OVA) through a combination of intraperitoneal injection and daily intranasal challenge in an awake condition. Penh was measured at each time point during sensitization, or a serial change in Penh value was followed after the final nasal challenge and the effect of treatment was assessed. Following sensitization and nasal challenge, the Penh value gradually increased and showed a significant difference on day 14. Changes in IgE, eosinophil infiltration into nasal mucosa, and OVA-induced symptoms all strongly correlated with the increase in Penh. On day 19, after OVA nasal provocation, Penh gradually increased and reached maximal values 25 min after the challenge. Pretreatment with dexamethasone or a histamine H1 blocker significantly suppressed this increase in Penh. We confirmed that intranasal OVA challenge did not induce bronchoconstriction by measuring airway resistance and bronchoalveolar lavage fluid, and through histological examination. These results clearly demonstrate that Penh could be a useful noninvasive indicator for studying nasal hypersensitivity.     

Tryptase in nasal lavage fluid after local allergen challenge: Relationship to histamine levels and TAME-esterase activity

The activation of mast cells is generally considered to be an important trigger mechanism in the immediate allergic response. This study focused on the determination of three markers of mast cell activation after an allergen challenge. Nasal allergen challenges were performed in 25 subjects with seasonal allergic rhinitis using three allergen doses increasing in 10-fold steps in a standardised nasal lavage model for the subsequent recovery of the markers of mast cell activation. The levels of histamine and tryptase in the nasal lavage fluid were determined using radioimmunoassays, while the TAME-esterase activity was determined using a radiochemical technique. The nasal symptoms obtained on challenge were assessed using a scoring technique. The allergen challenge resulted in significant increases in the levels of all three markers, tryptase, histamine and TAME-esterase. In the individual measurements after the challenges there was a highly significant correlation between the TAME-esterase levels and the tryptase levels (r = 0.71; P less than 0.001), while the generation of histamine and tryptase was not significantly correlated. When comparing the cumulative generation of the three markers, significant correlations were found between all three. Allergen challenges in six non-allergic controls using the same technique did not result in any increase in tryptase levels. The findings suggest that the determination of tryptase in nasal lavage fluid may be a valuable indicator of mast cell activation in the upper airways.     

Heparin attenuates symptoms and mast cell degranulation induced by AMP nasal provocation

BACKGROUND: Previous studies have shown that inhaled heparin attenuated the airway responses to allergen, exercise, and AMP bronchial provocation, possibly through an inhibition of mast cell activation. OBJECTIVE: The aim of this study was to provide the evidence of in vivo inhibition of human mast cell activation by heparin in a noninvasive model. METHODS: Nine atopic and 6 nonatopic subjects received placebo and unfractionated heparin sodium (5000 IU/mL) 15 minutes before an AMP nasal provocation in a double-blind crossover study design. The nasal lavage was collected from these subjects before or 3, 5, 15, or 30 minutes after the AMP nasal challenge, and concentrations of histamine and tryptase in the nasal lavage were measured. RESULTS: AMP nasal provocation produced considerable sneezing and induced a transient increase in histamine and tryptase release, with peak values achieved at 3 to 5 minutes after the challenge in all atopic subjects. Compared with placebo, inhaled heparin significantly attenuated the release of histamine and tryptase induced by AMP challenge (P=.012 and.004, respectively). Moreover, the AMP-induced sneezing was also inhibited by pretreatment with heparin (P=.016). In nonatopic subjects, AMP did not induce a significant increase in histamine and tryptase release on placebo-treated or heparin-treated days. CONCLUSION: These data suggest that AMP nasal provocation and AMP bronchial provocation cause mast cell mediator release in a similar fashion. In addition, the data support the hypothesis that inhaled heparin plays a protective role against AMP provocation by inhibition of mast cell activation.     

Rhinomanometry study of patients with respiratory allergy

To examine the accuracy of nasal allergic disease, we examined the results of skin tests, measurement of serum specific IgE (RAST), and the nasal response to nasal challenge in 886 patients clinically suspected of having allergic respiratory disease. Nasal responses were assessed by measuring nasal airway resistance by both active anterior and posterior rhinomanometry. Nasal airway resistance was determined 25 min. after intranasal nebulization of saline solution and after administration of increasing doses of allergen (maximum dose = 280 micrograms). The dose of allergen causing a 100% increase over the value obtained after saline (Ri) at a flow rate of 0.15 l.s-1 was taken as the threshold dose (Dl). Our findings were that active anterior and posterior rhinomanometry yield comparable results; in subjects with a positive response to antigen challenge, the increase in nasal airway resistance correlated well with the dose of allergen administered and a significant inverse relationship was found between Ri and Dl; 3) a high level of serum specific IgE accurately predicted nasal responsiveness to a particular allergen, whereas skin tests were often positive to allergens that had no detectable effect on the nasal resistance. We conclude that nasal allergen provocation tests with rhinomanometric measurement of nasal resistance is a useful procedure for diagnosis of nasal allergic disease.     

Effect of cetirizine, levocetirizine, and dextrocetirizine on histamine-induced nasal response in healthy adult volunteers

BACKGROUND: Cetirizine, an effective H1-receptor antagonist, is a racemate mixture of two enantiomers: levocetirizine (R enantiomer) and dextrocetirizine (S enantiomer). METHODS: To investigate the pharmacologic activity of the two enantiomers of cetirizine, we conducted a randomized, double-blind, four-way, crossover study to assess the effect of treatment with 5 mg levocetirizine, 5 mg dextrocetirizine, and 10 mg cetirizine and matched placebo, on histamine-induced changes in the nasal airways of 24 healthy volunteers. Four hours after a single oral intake, all subjects were challenged by nasal aerosol application with increasing doubling concentrations (from 0.25 to 32 mg/ml) of histamine in both nostrils. Nasal resistance was measured by passive anterior rhinomanometry (PAR), and changes in histamine threshold were calculated together with the absolute number of sneezes after each challenge. RESULTS: Both levocetirizine and cetirizine significantly attenuated the histamine-induced increase in nasal airway resistance by nearly 50% (from a median resistance of 2.51 Pa per cm3/s to 1.29 and 1.31 Pa per cm3/s, respectively) at the maximal concentration, and they concomitantly increased the histamine threshold by fourfold (from 8 to 32 mg/ml), compared with placebo. Sneezing was also attenuated by both levocetirizine and cetirizine. However, these antihistaminic effects were not seen with dextrocetirizine. CONCLUSIONS: This study shows a similar activity of levocetirizine and cetirizine on the inhibition of histamine-induced increase in nasal resistance, indicating that the antihistaminic properties of cetirizine are probably attributable to levocetirizine.     

Diagnostic value of a glass fibre-based histamine analysis for allergy testing in children

The aim of this study was to compare the diagnostic value of common allergy tests with basophil histamine release in 124 children with symptoms of asthma. The patients were evaluated by case history, skin prick test, RAST-analysis, and basophil histamine release using a glass fibre-based histamine assay to 10 common inhalant allergens. The bronchial provocation test was used as a reference of "true" IgE-mediated asthma. To compare the various diagnostic parameters each absolute test value was classified into a scoring system. The concordance between the tests varied between 85-97%. In general, the best concordance was found between basophil histamine release and RAST. Sensitivity, specificity and predictive values were calculated on the basis of 104 bronchial provocation tests. It was found that histamine release was the best single analysis, followed by RAST and prick testing. The sensitivity of RAST and histamine release was very high (1.00) for pollen and house dust mites. Histamine release showed a predictive value between 0.91 and 1.00 for pollen and house dust mites, thus indicating the possibility of omitting the bronchial provocation test. In the dander group histamine release gave the best sensitivity (0.91), however at the expense of specificity (0.64), whereas RAST and skin prick test gave a specificity of 1.00. In the mould group histamine release also showed the best diagnostic value. The combination of skin testing with histamine release or RAST was of no additional diagnostic help. It is concluded that the glass fibre-based histamine analysis, which makes routine histamine release testing possible, is a reliable diagnostic test in children.