Short-course subcutaneous treatment with PQ Grass strongly improves symptom and medication scores in grass allergy.

BACKGROUND: A modified grass allergen subcutaneous immunotherapy (SCIT) product with MicroCrystalline Tyrosine and monophosphoryl lipid-A as an adjuvant system (Grass MATA MPL [PQ Grass]) is being developed as short-course treatment of grass-pollen allergic rhinitis (SAR) and/or rhinoconjunctivitis. We sought to evaluate the combined symptom and medication score (CSMS) of the optimized cumulative dose of 27,600 standardized units (SU) PQ Grass in a field setting prior to embarking on a pivotal Phase III trial. METHODS: In this exploratory, randomized, double-blind, placebo-controlled trial subjects were enrolled across 14 sites (Germany and the United States of America). Six pre-seasonal subcutaneous injections of PQ Grass (using conventional or extended regimens) or placebo were administered to 119 subjects (aged 18-65 years) with moderate-to-severe SAR with or without asthma that was well-controlled. The primary efficacy endpoint was CSMS during peak grass pollen season (GPS). Secondary endpoints included Rhinoconjunctivitis Quality of Life Questionnaire standardized (RQLQ-S) and allergen-specific IgG4 response. RESULTS: The mean CSMS compared to placebo was 33.1% (p = .0325) and 39.5% (p = .0112) for the conventional and extended regimens, respectively. An increase in IgG4 was shown for both regimens (p < .01) as well as an improvement in total RQLQ-S for the extended regimen (mean change -0.72, p = .02). Both regimens were well-tolerated. CONCLUSIONS: This trial demonstrated a clinically relevant and statistically significant efficacy response to PQ Grass. Unprecedented effect sizes were reached for grass allergy of up to ≈40% compared to placebo for CSMS after only six PQ Grass injections. Both PQ Grass regimens were considered equally safe and well-tolerated. Based on enhanced efficacy profile extended regime will be progressed to the pivotal Phase III trial.

Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease: an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN).

Evidence that enables us to identify, assess, and access the small airways in asthma and chronic obstructive pulmonary disease (COPD) has led INTERASMA (Global Asthma Association) and WAO to take a position on the role of the small airways in these diseases. Starting from an extensive literature review, both organizations developed, discussed, and approved the manifesto, which was subsequently approved and endorsed by the chairs of ARIA and GA2LEN. The manifesto describes the evidence gathered to date and defines and proposes issues on small airway involvement and management in asthma and COPD with the aim of challenging assumptions, fostering commitment, and bringing about change. The small airways (defined as those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and COPD and are the major determinant of airflow obstruction in these diseases. Various tests are available for the assessment of the small airways, and their results must be integrated to confirm a diagnosis of small airway dysfunction. In asthma and COPD, the small airways play a key role in attempts to achieve disease control and better outcomes. Small-particle inhaled formulations (defined as those that, owing to their size [usually <2 µm], ensure more extensive deposition in the lung periphery than large molecules) have proved beneficial in patients with asthma and COPD, especially those in whom small airway involvement is predominant. Functional and biological tools capable of accurately assessing the lung periphery and more intensive use of currently available tools are necessary. In patients with suspected COPD or asthma, small airway involvement must be assessed using currently available tools. In patients with subotpimal disease control and/or functional or biological signs of disease activity, the role of small airway involvement should be assessed and treatment tailored. Therefore, the choice between large- and small-particle inhaled formulations must reflect the physician's considerations of disease features, phenotype, and response to previous therapy. This article is being co-published in Asthma Research and Practice and the World Allergy Organization Journal.

Manifesto on small airway involvement and management in asthma and chronic obstructive pulmonary disease: an Interasma (Global Asthma Association - GAA) and World Allergy Organization (WAO) document endorsed by Allergic Rhinitis and its Impact on Asthma (ARIA) and Global Allergy and Asthma European Network (GA2LEN).

Evidence that enables us to identify, assess, and access the small airways in asthma and chronic obstructive pulmonary disease (COPD) has led INTERASMA (Global Asthma Association) and WAO to take a position on the role of the small airways in these diseases. Starting from an extensive literature review, both organizations developed, discussed, and approved the manifesto, which was subsequently approved and endorsed by the chairs of ARIA and GA2LEN. The manifesto describes the evidence gathered to date and defines and proposes issues on small airway involvement and management in asthma and COPD with the aim of challenging assumptions, fostering commitment, and bringing about change. The small airways (defined as those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and COPD and are the major determinant of airflow obstruction in these diseases. Various tests are available for the assessment of the small airways, and their results must be integrated to confirm a diagnosis of small airway dysfunction. In asthma and COPD, the small airways play a key role in attempts to achieve disease control and better outcomes. Small-particle inhaled formulations (defined as those that, owing to their size [usually <2 µm], ensure more extensive deposition in the lung periphery than large molecules) have proved beneficial in patients with asthma and COPD, especially those in whom small airway involvement is predominant. Functional and biological tools capable of accurately assessing the lung periphery and more intensive use of currently available tools are necessary. In patients with suspected COPD or asthma, small airway involvement must be assessed using currently available tools. In patients with subotpimal disease control and/or functional or biological signs of disease activity, the role of small airway involvement should be assessed and treatment tailored. Therefore, the choice between large- and small-particle inhaled formulations must reflect the physician's considerations of disease features, phenotype, and response to previous therapy. This article is being co-published in Asthma Research and Practice and the World Allergy Organization Journal.

Quality of life in patients with persistent allergic rhinitis treated with montelukast alone or in combination with levocetirizine or desloratadine.

BACKGROUND: Persistent allergic rhinitis often impairs quality of life. OBJECTIVE: We assessed the extent to which treating persistent allergic rhinitis with montelukast, desloratadine, and levocetirizine alone or in combination improved quality of life. METHODS: A 32-week randomized, double-blind, placebo-controlled, crossover study was performed in 2 arms: 20 patients received montelukast 10 mg/d and/or desloratadine 5 mg/d or placebo; 20 patients received montelukast 10 mg/d and/or levocetirizine 5 mg/d or placebo. The treatment periods were separated by 2-week washout periods. Quality of life was assessed on the day before starting treatment and on the last day of each treatment period using the Rhinoconjunctivitis Quality of Life Questionnaire. Sleep problems were also assessed. RESULTS: In the desloratadine plus montelukast arm, the mean (SEM) quality of life score before treatment was 3.1 (0.41). After placebo, this score was 2.16 (0.43), after desloratadine it was 1.79 (0.38), after montelukast it was 1.48 (0.37), and after montelukast plus desloratadine it was 1.59 (0.37). In the montelukast plus levocetirizine arm, the mean quality of life score before treatment was 2.58 (0.49). After placebo it was 1.78 (0.46), after levocetirizine it was 1.38 (0.42), after montelukast it was 1.36 (0.37), and after montelukast plus levocetirizine it was 1.26 (0.39). CONCLUSIONS: Placebo, montelukast, desloratadine and levocetirizine significantly improved quality of life. Combining montelukast with either levocetirizine or desloratadine gave additional benefits in comparison to each agent alone and could be considered for patients whose quality of life is impaired by persistent allergic rhinitis.

[Histamine releasing and immunomodulating activity of dental restorative materials].

Histamine releasing and immunomodulating activity of the following dental restorative materials (DRM) - Prizmafil, Filtek Z250, XRV Herculite Prodigy, Glasiosite, Te-Econol, Valux Plus, Polofil Supra were studied. It was shown that DRM under study as a rule did not possess the ability to release histamine (H) from human blood basophile (BB) excluding Filtek Z250 which release H from BB in patients with allergy and sound donors. The studied DRM implanted under mouse skin were able to modulate immune response to the allergen, at that some of them increased antibodies of IgE-class forming and other suppressed immune response caused by IgG-antibody forming. Received data have certain significance in the scheme of safety evaluation and individual assessment of DRM having acceptable biocompatibility for specific patient.

Differential expression of monocyte CD163 in single- and dual-asthmatic responders during allergen-induced bronchoconstriction.

BACKGROUND: Mononuclear phagocytes play an important role in modulating inflammatory reactions in response to antigen challenge. OBJECTIVE: To investigate the regulation of CD163, a marker of anti-inflammatory macrophages, during Dermatophagoides pteronyssinus (Dp)-induced bronchoconstriction. METHODS: Among 110 Dp-sensitive patients who underwent bronchial challenge with Dp, there were 51 dual responders (DR), 32 single responders (SR) and 27 non-responders (NR). Monocyte expression of CD14 and CD163 was evaluated by flow cytometry. Exhaled NO (eNO) concentration was determined on-line using a chemiluminescence analyser. In 21 DR, nine SR and 13 NR-soluble CD163 in plasma was measured by ELISA before, 1, 8 and 24 h after the challenge. RESULTS: In DR, the baseline expression of monocyte CD163 and eNO were significantly greater than in SR and NR. A pattern of (1) decreased monocyte CD163 expression, (2) unchanged sCD163 and (3) increased eNO in DR was contrasted by a pattern of (1) increased CD163 expression, (2) increased sCD163 and (3) unchanged eNO in SR. During allergen challenge, the changes in monocyte CD163 expression and sCD163 inversely correlated with the changes in eNO. CONCLUSION: Both pro-inflammatory and anti-inflammatory responses to allergen challenge are uniquely expressed among SR and DR.

IgE, allergic diseases, and omalizumab.

Immunoglobulin E (IgE) plays a central role in the development of allergic diseases. In sensitized individuals, IgE antibodies bind to receptors on mast cell and basophil surfaces, releasing preformed and newly generated mediators that initiate an immunologic cascade and inflammatory symptoms. Omalizumab (Xolair) is a humanized monoclonal antibody designed to bind specifically to IgE. It was approved by the United States Food and Drug Administration in 2003 for the treatment of patients with moderate-to-severe persistent asthma that is inadequately controlled with inhaled corticosteroids (ICS) and who have a positive skin test or in vitro reactivity to a perennial aeroallergen. In clinical trials in such patients, omalizumab reduced the incidence of asthma exacerbations, severe exacerbations, the use of rescue medication, and improved both symptoms and quality of life (QOL).

Platelet activation in allergic asthma patients during allergen challenge with Dermatophagoides pteronyssinus.

BACKGROUND: Animal models of allergic asthma indicate that intravascular platelet activation is necessary for the development of allergen-induced chronic airway inflammation. OBJECTIVE: To evaluate whether the development of a late asthmatic response (LAR) in allergic asthma patients challenged with a relevant allergen is consequent to platelet activation. METHODS: Thirty-three house dust mite sensitive asthmatic patients were challenged intrabronchially with Dermatophagoides pteronyssinus (Dp) extract. Twelve non-atopic healthy subjects (HC) were used as controls. Platelet count and plasma levels of beta-thromboglobulin (beta-TG), platelet factor-4 (PF-4) and soluble P-selectin (sP-selectin) were assessed before the challenge (T(0)) and 30 min (T(EAR)), 6 h (T(LAR)) and 24 h (T(24)) after the challenge. RESULTS: Eleven patients responded to allergen challenge with an isolated early asthmatic response (single responders, SR). In 22 patients dual asthmatic response was demonstrated (dual responders, DR). At T(0) neither the platelet count nor the mean plasma level of beta-TG in DR or SR were different from HC, the mean plasma level of PF-4 in SR was significantly greater than in HC (P=0.01) or DR (P=0.001), the mean plasma level of sP-selectin was significantly greater in DR than in HC (0.0002) but not statistically different from SR (P=0.055). A significant decrease in the platelet count and increase in the plasma level of all the studied markers was seen at T(EAR), which was followed by a gradual return to the baseline values in the SR. Elevated plasma levels of platelet activation markers and decreased platelet count were seen in the DR even at T(24). Strong correlation was found between the increase in plasma concentration of beta-TG at T(EAR) and the maximum fall in forced expiratory volume in 1 s at T(LAR) (r=-0.57; P=0.0006). CONCLUSION: In allergic asthma patients development of prolonged airway inflammation after allergen challenge is associated with intravascular platelet activation.

Aspirin-triggered 15-HETE generation in peripheral blood leukocytes is a specific and sensitive Aspirin-Sensitive Patients Identification Test (ASPITest).

BACKGROUND: We have previously demonstrated that aspirin triggers specific generation of 15-hydroxyeicosateraenoic acid (15-HETE) from nasal polyp epithelial cells and peripheral blood leukocytes (PBL) from aspirin-sensitive (AS) but not aspirin-tolerant (AT) patients with asthma/rhinosinusitis. The goal of this study was to assess the diagnostic value of ASA-induced 15-HETE generation measurement to identify AS patients. METHODS: PBL were obtained from 43 AS patients with asthma and rhinosinusitis, 35 AT asthmatics and 17 healthy control (HC) subjects. PBL were incubated with 2-200 muM aspirin (ASA) and 15-HETE release was measured in cell supernatants with competitive ELISA. RESULTS: Unstimulated PBL from all three groups of patients generated similar amount of 15-HETE. Incubation with 200 microM ASA resulted in an increase in an 15-HETE generation (mean increase +421%) in AS-asthmatics but small and nonsignificant response in AT-asthmatics or control subjects. Receiver operating curve (ROC) analysis revealed that the sensitivity of the test for confirmation of ASA-sensitivity was 83% and the specificity 82%. Positive predictive value was 0.79 and negative predictive value was 0.86. Naproxen induced a significant increase in 15-HETE only in some AS-asthmatics, but not in AT-asthmatics. CONCLUSION: Our data demonstrate that ASA-induced 15-HETE generation by PBL is a specific and sensitive aspirin-sensitive patients identification test (ASPITest).

Inhibition of nasal polyp mast cell and eosinophil activation by desloratadine.

Nasal polyp tissue which contains mast cells and eosinophils is similar to the inflamed airway mucosa in cellular composition and mediator content. This investigation assessed the effect of desloratadine (DL), on activation of cells in nasal polyp tissue. Polyps were obtained from 22 patients with chronic rhinosinusitis [nine aspirin acetylosalitic acid (ASA)-sensitive and 13 ASA-tolerant]. Polyp tissue was dispersed by digestion, and preincubated with DL and incubated with anti-immunoglobulin E (IgE) or calcium ionophore. LTC4, eosinophil cationic protein (ECP) and tryptase concentrations in supernatants were measured by immunoassays. Desloratadine (1, 10 and 50 microM) inhibited calcium ionophore-induced LTC4 release by a mean of 29%, 50% and 63% respectively, and anti-IgE-induced LTC4 release by a mean of 27%, 35% and 39% respectively. Calcium ionophore-induced tryptase release was inhibited 60% and 69% by 10 and 50 microM of DL, respectively, and anti-IgE-induced tryptase release was inhibited 33%, 47% and 66% for 1, 10 and 50 microM of DL. Desloratadine 10 microM and 50 microM inhibited ECP release by and 45% and 48% respectively. Polyp tissue from ASA-sensitive patients when compared with ASA-tolerant patients released at baseline significantly more ECP (medians 120.0 microg/ml, range: 69.0-182.0 vs 63.4 microg/ml, range: 3.7-172.0; P <0.05), but similar amounts of tryptase and LTC4. This study demonstrated that DL inhibits activation of both eosinophils and mast cells derived from a site of airway mucosal inflammation.

Prevalence of skin test reactions to natural rubber latex in hospital personnel in Russia and eastern Europe.

BACKGROUND: Allergic reactions to natural rubber latex have increased during the past 10 years, especially in many health care workers (HCWs) who have high exposure to latex allergens. The prevalence of skin test reactions to natural rubber latex in Russia, the Commonwealth of Independent States (CIS), and eastern Europe is unknown. OBJECTIVE: The purpose of this study was to determine the prevalence of skin test reactivity to natural rubber latex in a population of HCWs exposed to latex. METHODS: Nine hundred one HCWs regularly exposed to latex were evaluated using an allergy history questionnaire. Subjects were tested for latex allergy by titrated skin prick test with a biologically standardized latex extract. The diagnosis of latex allergy was defined by the presence of clinical symptoms when exposed to latex along with a positive skin prick test to latex. RESULTS: Forty-nine (5.4%) HCWs were skin test-positive to latex. Seventeen (1.9%) HCWs were classified as latex-allergic based upon positive skin tests to latex associated with allergy symptoms with exposure. Seven of 901 HCWs had experienced anaphylactic reactions to latex. The most frequently reported symptom related to latex exposure was contact urticaria. CONCLUSIONS: The prevalence of latex allergy among HCWs in Russia, the CIS, and adjacent eastern European countries is considerably less than reported in HCWs exposed to latex in western Europe and the United States. The low prevalence of latex allergy in Russia and the CIS suggests that lessened exposure to natural latex powdered gloves may diminish the prevalence of latex sensitization in HCWs in Russia and the CIS.

Latex aeroallergen quantification in hospitals of Moscow, Russia.

BACKGROUND: Health care workers (HCWs) who use latex gloves regularly are at a significant risk for developing allergic sensitization to natural rubber latex (NRL) proteins. The airborne route of exposure presents a hazard for sensitization and subsequent allergic symptoms. OBJECTIVE: The purpose of this study was to measure the content of the NRL proteins in the air of work areas (laboratories, treatment rooms, operating rooms, examination rooms, and dentist's treatment rooms) in eight Moscow hospitals where the employees used powdered latex gloves. METHODS: The air samples were collected by a volumetric filtration method using a static air sampler at a flow rate of 3 L/second. Airborne particles were collected onto polytetrafluoroethylene filters rated 99.9% efficient at 0.3 microm. The NRL allergens were extracted from the air filter samples in phosphate-buffered saline and quantified by an inhibition immunoassay using a five-person pool of sera containing latex-specific human immunoglobulin E. RESULTS: The airborne latex allergen concentrations in 11 areas (including positive control) where latex gloves were used varied from 5 to 26 ng/m3. Conversely, in 12 areas where latex gloves were seldom used or where powdered-free latex gloves were used allergen levels were not detectable (including two negative controls). The highest concentration of latex allergen (26 ng/m3) was found in an examination room of a gynecology department. Low and moderate concentrations were detected in most operating rooms, and low concentrations in the laboratories and treatment rooms. CONCLUSIONS: This study indicates that, in general, the airborne NRL concentrations in the work areas of Moscow hospitals are rather low compared with NRL concentrations reported from American hospitals and are dependent on the intensity of latex glove usage.

Mediator antagonists in the treatment of allergic disease.

New approaches to allergic inflammation include specific cytokine antagonists and monoclonal antibodies against IgE, against chemokines, and against adhesion molecules. Currently available therapies, such as leukotriene antagonists, may soon be approved for allergic rhinitis. New generation antihistamines such as desloratadine have wide-ranging anti-allergic, anti-inflammatory profiles, including suppression of cytokine, chemokine, and adhesion molecule expression. Recent desloratadine studies have demonstrated that this highly potent H1 receptor antagonist consistently provides relief of nasal congestion and may provide benefits similar to montelukast in mild asthma patients. New generation intra-nasal corticosteroids such as fluticasone and mometasone provide high corticosteroid potency while being minimally bioavailable when administered as intranasal preparations. Future advances in allergy therapy also include improved T-cell selective formats of immunotherapy. The range of therapies for allergic rhinitis is likely to substantially increase in the coming years.

Appropriate and inappropriate use of immunotherapy.

OBJECTIVE: The primary objective of this review is to discuss indications for appropriate and inappropriate use of allergen immunotherapy (IT), including discussion of contraindications, adverse events, and alternative protocols and methods. DATA SOURCES: A review of the literature on indications, contraindications, adverse events, and alternative methods and protocols associated with allergen IT was conducted. STUDY SELECTION: The opinion of the author was used to select and review relevant data. RESULTS: Clinical trials have proven the benefit of allergen IT, for allergic rhinitis, asthma, and anaphylaxis because of stinging insects, such as Hymenoptera and fire ants. Allergen IT may improve quality of life and decrease medication requirement for allergic rhinitis and asthma, especially for younger patients, and probably will assist in the prevention of the progression of allergic disease from rhinitis to asthma. Subcutaneous allergen IT is well established as clinically effective through multiple, blinded, placebo-controlled studies. The data for alternate therapies and routes of therapy are extensively reviewed and critiqued. CONCLUSIONS: Allergen IT is a highly valuable form of treatment of IgE-mediated diseases. Documentation of sensitivity to allergen sensitization associated with symptoms is critical before use of allergen IT. Symptoms should also be of sufficient duration and severity to warrant IT. Before allergen IT is used, there must be an available allergen extract that is suitable for treatment of the relative sensitivity. It is essential for patients receiving allergen IT to understand the treatment principle, the frequency of injections, the duration of treatment, the risk and signs of adverse events, the magnitude of the efficacy, and the essential nature of patient compliance. Subcutaneous allergen IT is the only current mode of therapy in the United States that has been shown to be effective.

Assessment of IgE allergen specificity among latex-allergic health care workers: review of IgE-binding components of various latex extracts.

BACKGROUND: Allergic reactions to natural rubber latex have increased during the past 10 years, especially in many health care workers who have high exposure to latex allergens both by direct skin contact and by inhalation of latex particles from powdered gloves. Development of satisfactory diagnostic methods to verify the presence of latex allergy in health care workers requires characterization of the immunoreactive proteins in latex products and identification of specific IgE antibodies in sensitized patients. A number of different latex preparations are now available for in vitro evaluations. OBJECTIVES: Utilizing different in vitro methods, this study examines IgE sensitization to components of latex in a selected population of hospital employees, employing a raw natural latex glove extract and various commercial latex extracts. METHODS: Two hundred hospital employees exposed to latex were evaluated using an allergy history questionnaire. To further identify sensitized patients, two different specific IgE tests and leukocyte histamine release tests were performed using a panel of latex extracts obtained from different manufacturers. Sodium dodecylsulfate polyacrylamide electrophoresis (SDS-PAGE) profiles were obtained. Sera from 34 subjects suspected to be latex-sensitized were IgE immunoblotted to assess the presence of IgE antibodies directed toward specific latex proteins. RESULTS: Thirty-four participants (17%) were considered sensitized to latex by a positive clinical history in conjunction with positive specific IgE tests (18 individuals) and/or positive histamine release tests (26 individuals). Significant extract differences in both the histamine release response profile and the frequency of positive test results were noted in the histamine release test. Significant individual differences in patients' latex epitope-specificity were found by IgE immunoblotting, substantiated by sodium dodecylsulfate polyacrylamide profiles revealing differences in protein band patterns among the various extracts. The IgE immunoblots indicated that the majority of patients reacted to proteins with molecular weights of 14, 21, 30 to 35, and 42 kD; the 30 to 35 kD protein being predominant. Seven subjects (22%) of the 34 considered to be latex-sensitized did not reveal binding of specific IgE in immunoblots. One latex extract (Stallergene) with the widest IgE-reacting protein repertoire identified the majority of subjects (63%) as latex sensitive by leukocyte histamine release and also provided the best quantitative histamine release test results. CONCLUSION: Only by testing with a combination of latex extracts were all sensitized individuals identified. This study demonstrates that currently several in vitro methods may be necessary to detect IgE sensitization to latex. Latex extracts to be employed in future skin tests must contain a wide epitope repertoire of IgE-binding proteins to identify all latex-sensitized individuals.

Effect of misoprostol on the secretion of histamine from basophils of whole blood.

BACKGROUND: Misoprostol (MSP), the synthetic prostaglandin E1 (PGE1) analog, possesses multifunctional features, including modulating some inflammatory aspects of immune and allergic disorders. OBJECTIVES: To investigate the effect of MSP on histamine release (HR) from basophils of whole blood using anti-IgE, specific allergens, and calcium ionophore. METHODS: The study was performed using the automated glass fiber-based whole blood leukocyte histamine release test (LHRT). RESULTS: Very low concentrations of MSP produced a marked inhibition of HR induced with anti-IgE. Maximum inhibition was observed at 10-9 M. It was also shown that the levels of HR inhibition with MSP varied at different incubation times. The greatest inhibition of HR was noted at 1 to 2 hours of incubation at MSP concentrations of 10-8 and 10-9 M, respectively. Incubation of blood from allergic patients at the optimal MSP concentration and optimal elapsed time (2 hours) resulted in significant reductions of allergen-specific HR induced by both Timothy pollen grass allergen and D.pteronissinus. Incubation of blood with varying concentrations of MSP and subsequent stimulation with calcium ionophore A23187 also inhibited HR from basophils. In the latter case, the most effective concentrations of MSP ranged from 10-8 to 10-6 M. CONCLUSIONS: This study demonstrated that MSP can inhibit basophil HR indicating a potentially beneficial role of PGE1 analogs as pharmacotherapy for allergic diseases.

Second-generation antihistamines: the risk of ventricular arrhythmias.

Some second-generation antihistamines, notably terfenadine and astemizole, have been associated with prolongation of the QT interval and the development of torsades de pointes, a potentially fatal ventricular arrhythmia. This rare adverse event has been associated with greatly elevated blood levels of these agents, resulting from drug overdose, hepatic insufficiency (dysfunction), or interactions with other drugs that inhibit their metabolism. This paper reviews the data concerning the effects of selected second-generation antihistamines on cardiac conduction, particularly the QT interval, to evaluate whether ventricular arrhythmias are a class effect of these agents. Electrocardiographic studies indicate that terfenadine and astemizole, but not loratadine or cetirizine, prolong the QT interval in laboratory animals. In vitro studies demonstrate that terfenadine and astemizole block the cardiac K+ channels, leading to delayed ventricular repolarization and QT-interval prolongation; in contrast, neither loratadine nor its metabolite, desloratadine, significantly inhibits cardiac K+ channels at clinically achievable blood levels. Studies in human volunteers confirm the absence of electrocardiographic effects of azelastine, cetirizine, fexofenadine, and loratadine administered at several times the recommended dose or concomitantly with agents that inhibit their metabolism and elimination. In conclusion, the data indicate that the potential to cause ventricular arrhythmias is not a class effect of second-generation antihistamines and that loratadine, cetirizine, azelastine, and fexofenadine are not associated with torsades de pointes or other ventricular arrhythmias.

[Chemical modification of allergen leading to changes in its epitopic activity]. / Khimicheskaia modifikatsiia allergena, vedushchaia k izmeneniiu ego épitopnoi aktivnosti.

Modification of a model allergen ovalbumin (OA) with succinylation led to a decrease of its allergenicity measured by passive cutaneous anaphylaxis reaction, RAST inhibition assay and basophil histamine release. Modified OA stimulated OA-specific T-cell hybrid 3DO-548 to produce IL-2 at the same level as in case of non-modified OA. Modified OA did not induce anti-OA IgE, but did induce anti-OA IgG antibodies. This approach to chemical modification of allergen-selective blockade of B-cell epitopes while not affecting T-cell epitopes suggests new opportunities in creation of safe and effective allergovaccines.