Etiopathogenesis and Management of Perennial Allergic Rhinitis

The Use and Efficacy of Oral Phenylephrine Versus Placebo Treating Nasal Congestion Over the Years on Adults: A Systematic Review

Nasal congestion is a common issue stemming from various factors such as allergies and anatomical variations. Allergic rhinitis frequently leads to nasal congestion. The pathophysiology involves inflammation, swelling, and mucus production in the nasal mucosa. Multiple treatments are available, including oral phenylephrine, an over-the-counter or prescription option. However, the effectiveness and safety of phenylephrine have been subjects of debate. This systematic review aims to provide an updated perspective on the efficacy of oral phenylephrine versus placebo in addressing nasal congestion in adults. We conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, a systematic review involving searches on PubMed, Cochrane, and Scopus databases. Inclusion/exclusion criteria were defined to identify high-quality studies. The focus was on randomized controlled trials (RCTs) and case-control studies published in English between 1998 and 2023, involving adult populations. The interventions compared oral phenylephrine with placebo or standard care, with outcomes centering on changes in nasal congestion symptoms and nasal airway resistance. We identified four articles that met the criteria. These studies exhibited varied designs and populations. The findings consistently indicated that phenylephrine was not more effective than a placebo in relieving nasal congestion. This systematic review demonstrates that oral phenylephrine did not offer substantial relief from nasal congestion compared to a placebo in adults. The studies featured diverse designs, yet the prevailing conclusion was that phenylephrine's efficacy was limited. Safety assessments showed no life-threatening adverse events, with common side effects including headaches and mild discomfort. In summary, this systematic review indicates that oral phenylephrine is not significantly more effective than a placebo in alleviating nasal congestion in adults. Clinicians should explore alternative treatment options, considering the review's limitations. Additional research may be needed to clarify the role of oral phenylephrine in managing nasal congestion.

Assessment of the Prevalence of the Use of Nasal Decongestants Among the General Population in Saudi Arabia

Background A topical nasal decongestant (NDC) is widely prescribed in ENT practice and used as self-medication because it is available over the counter, which makes it an easily accessible medication. Due to its common and long-term use, it is associated with serious nasal complications. It is commonly self-administrated in many otolaryngology diseases like the common cold, sinusitis, and acute or chronic rhinitis. The long-term usage of nasal decongestants is associated with significantly increased side effects. Aim To assess the prevalence of the usage of nasal decongestants among the general population in Saudi Arabia ad the pattern of its use. Methodology A questionnaire-based, cross-sectional survey was applied to level all available populations in Saudi Arabia. Participants with ages aged 10 to 60 years old in Saudi Arabia were invited to participate in the survey. Data were collected from participants using a predesigned online questionnaire. The questionnaire included the participant's demographic data, NDC use, and pattern of use. The questionnaire was uploaded online by researchers and their friends using social media platforms. Results A total of 1456 participants completed the study questionnaire. Participants ages ranged from 10 to 60 years with a mean age of 26.9 ± 12.4 years old. Exact 585 (40.2%) participants were males and 1270 (87.2%) were from urban regions. A total of 657 (45.1%) respondents reported using nasal decongestants while 799 (54.9%) did not use NDC. As for the duration of use, 70.8% used NDC for less than five days and 13.5% used it for 5-15 days. The most reported causes of using NDC were nasal obstruction (62.7%) and common cold (25.7%). Conclusions In conclusion, the study revealed that the frequency of using nasal decongestants was common (45.1%) in the study. More efforts should be paid to improve public awareness regarding indications, duration of use, and method of using nasal decongestants to avoid rebound reactions that may affect patients' daily life activities.

Effects of early life exposure to home environmental factors on childhood allergic rhinitis: Modifications by outdoor air pollution and temperature

BACKGROUND

There is growing evidence that allergic rhinitis (AR) is associated with indoor environmental factors, but their role in childhood AR during early life remains unclear.

OBJECTIVE

To investigate the association of preconceptional, prenatal, early postnatal, and current exposure to home environmental factors with childhood AR, and to further explore whether this association can be interacted by outdoor air pollution and temperature.

METHODS

A retrospective cohort study of 8689 preschool children was conducted during 2019-2020 in Changsha, China. A standard questionnaire was used to collect data on each family's health outcomes and home environments. We considered home environmental exposures during one year before conception, pregnancy, first year of life, and past year. Associations of indoor air pollution and allergens with AR were assessed by multiple logistic regression models.

RESULTS

Pre-birth exposure to indoor air pollution emitted by new furniture or redecoration and dampness related allergen derived from mold/damp stains and mold/damp clothes or bedding during 1 year before conception and pregnancy was significantly associated with increased AR, with adjusted ORs (95% CI) ranging from 1.35 (1.05-1.75) to 1.87 (1.55-2.27). Childhood AR was also significantly related with post-birth exposure to dampness related indoor allergen including mold/damp stains and mold/damp clothes or bedding in first year and past year and pollen allergen including total and nonflowing plants in past year, with a range of ORs (95% CI) from 1.20 (1.01-1.42) to 1.79 (1.42-2.27). We identified that pre-birth, particularly in utero exposure to both indoor air pollution from renovation and dampness related allergens, played a key role in AR development compared to post-birth exposures, and accumulative effect was observed with the highest risk of AR. High exposure to traffic-related air pollution (TRAP) including outdoor PM_2.5, NO₂, CO, and O₃, as well as living near traffic road not only significantly increased adverse effect of home environmental factors but also decreased protective effect of household dogs on childhood AR. Early life exposure to low temperature in pregnancy and high temperature in first year significantly increased AR risk of home environmental exposure. Sensitivity analysis indicated that some sub-groups were more susceptible to AR risk of home environmental exposure.

CONCLUSION

Our study suggests that pre-birth exposure to home environmental factors played an important role in AR development and this effect can be interacted by TRAP and temperature, which supports a hypothesis of "(pre)fetal origin of childhood AR".

Plant-Derived Lactobacillus paracasei IJH-SONE68 Improves Chronic Allergy Status: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

We have recently demonstrated that the exopolysaccharides (EPSs) produced by a plant-derived lactic acid bacterium, Lactobacillus paracasei IJH-SONE68, prevent and ameliorate allergic reaction on contact in dermatitis model mice. In the present study, we conducted a clinical trial using a capsule containing spray-dried powder from pineapple juice broth fermented with the LAB strain as an experimental diet. The clinical trial was conducted as a double-blind and placebo-controlled randomized comparative study from May 2019 to July 2021. Males and females between the ages of 21 and 70 who experience chronic allergies participated in the study. Sixty subjects were instructed to orally take a capsule containing the IJH-SONE68 powder or placebo, every day for 12 weeks. After the clinical trial was over, the scores based on subjects' self-assessment of allergic status were significantly improved in the intervention group, as compared with the placebo group. Some serum biochemicals associated with inflammation response were also significantly improved by intake of the experimental diet. In conclusion, the IJH-SONE68-derived EPS improves chronic allergy status in humans and is expected to decrease their inconvenience.

Influence of MP 29-02 on ciliary beat frequency in human epithelial cells in vitro

PURPOSE

MP 29-02, which contains fluticasone propionate and azelastine hydrochloride, is used as a topical nasal application for the treatment of seasonal and perennial allergic rhinitis. Although a multitude of data is available on the clinical symptom reduction and treatment safety of MP 29-02, the effect of MP 29-02 on ciliary beat frequency (CBF) has not been evaluated thus far.

METHODS

MP 29-02-containing solution was applied at concentrations of 2.5, 5, 10, and 20% to 14 healthy subjects, and nasal ciliated epithelial cells were then visualized using a phase-contrast microscope. CBF was measured after the application of MP 29-02. For a comparison, fluticasone propionate was used. CBF measurements were then performed for 15 min at 22 °C. Ringer's solution was applied as a negative control.

RESULTS

MP 29-02 significantly reduced CBF at all the tested concentrations compared with that of the control group within the observation time. At a 2.5% concentration, MP 29-02 significantly reduced CBF from 6.81 Hz (SD ± 1.35 Hz) at baseline to 4.88 Hz (SD ± 1.52 Hz, p < 0.001) after 15 min. In contrast, for fluticasone propionate, a significant reduction was observed only with the 20% concentration after 5, 10, and 15 min.

CONCLUSIONS

MP 29-09 significantly reduced CB, with an almost linear relationship between the MP 29-09 concentration and reduction in CBF. For fluticasone propionate, a significant reduction of CBF was observed only at the highest analyzed concentration. The findings have implications for the long-term use of the MP 29-02. Yet, further clinical studies are needed to confirm these results in vivo, especially in patients with seasonal or perennial allergic rhinits.

Association between two polymorphisms of histamine-metabolising enzymes and the severity of allergic rhinitis in a group of Mexican children

BACKGROUND

It has been suggested that polymorphisms of histamine metabolising enzymes can be a risk factor for developing histamine-involving diseases. The aim of the present study is to research the possible association between two functional single nucleotide polymorphisms (SNPs): C314T in the Histamine-N-Methyl Transferase gene and C2029G in the Diamine Oxidase gene, with the severity of allergic rhinitis and the number of allergic diseases, in a group of allergic Mexican children.

METHODS

We studied 154 unrelated allergic children. SNPs were analysed by RT-PCR. The total serum IgE was measured by chemiluminescence and the serum histamine by ELISA. We used logistic regression analysis to determine OR.

RESULTS

Patients carrying the mutant allele for any SNP had more risk to develop higher rhinitis severity or a bigger number of allergic diseases. Haplotype analysis revealed that this effect is synergistic. In patients carrying one or two mutant alleles, serum histamine levels were higher than those of patients carrying only wild alleles. Serum IgE levels were not associated with the presence of mutant alleles.

CONCLUSION

The presence of these SNPs in patients with allergic rhinitis can lead to higher serum histamine, therefore to a higher risk of developing more severe symptoms or more associated allergic diseases, even if the serum IgE remains low.

Recent pharmacological developments in the treatment of perennial and persistent allergic rhinitis

INTRODUCTION

Allergic rhinitis (AR) has a major negative impact on patients' quality of life (QoL) and carries a high socio economic burden. This is particularly the case for patients who experience symptoms for extended periods of time (i.e. those with perennial (PAR) or persistent AR (PER), depending on the classification system used). This review covers available pharmacological advances and recent developments in the treatment of PAR or PER.

AREAS COVERED

Pharmacological AR treatment is used to reduce symptom burden and help restore patients' normal daily routine. Traditionally, non-sedating antihistamines and intranasal corticosteroids (INS) were the two drug classes recommended for use first line. These, along with antileukotrienes, decongestants, mast cell stabilizers and anticholinergics, constituted the bulk of the AR treatment arsenal. MP-AzeFlu (Dymista®, Meda, Solna, Sweden) is the most recent addition to that arsenal. It is a novel intranasal formulation of azelastine hydrochloride (AZE) and fluticasone propionate (FP) delivered in a single spray and has surpassed available therapies in terms of symptom control and treatment response. Other relatively new treatments for PAR or PER include H3 antihistamines, toll-like receptor (TLR) agonists, cellulose powders and micro-emulsions, novel biomolecular formulations and omalizumab. Each of these new additions is reviewed here.

EXPERT OPINION

A new AR drug class has recently been introduced (i.e. RO1AD58). Currently MP-AzeFlu is the only treatment option within this drug class. It can be estimated that combination treatments like MP-AzeFlu will become the mainstay of PAR and PER therapy since use will result in better compliance, improved efficacy over INS and a faster response together with good levels of tolerability. The challenge is to find other equally, or more effective, combination treatments, as has been the therapeutic standard in bronchial asthma for decades. The potential of biologics, as well as TLR-agonists and other new treatment options needs to be further evaluated.

Mast cell histamine promotes the immunoregulatory activity of myeloid-derived suppressor cells

It has been shown recently that MCs are required for differential regulation of the immune response by granulocytic versus monocytic MDSCs. Granulocytic MDSCs promoted parasite clearance, whereas monocytic MDSCs enhanced tumor progression; both activities were abrogated in MC-deficient mice. Herein, we demonstrate that the lack of MCs also influences MDSC trafficking. Preferential trafficking to the liver was not seen in MC-deficient mice. In addition, evidence that the MC mediator histamine was important in MDSC trafficking and activation is also shown. MDSCs express HR1-3. Blockade of these receptors by HR1 or HR2 antagonists reversed the histamine enhancement of MDSC survival and proliferation observed in cell culture. In addition, histamine differentially influenced Arg1 and iNOS gene expression in MDSCs and greatly enhanced IL-4 and IL-13 message, especially in granulocytic MDSCs. Evidence that histamine influenced activity seen in vitro translated to in vivo when HR1 and HR2 antagonists blocked the effect of MDSCs on parasite expulsion and tumor metastasis. All of these data support the MDSC-mediated promotion of Th2 immunity, leading to the suggestion that allergic-prone individuals would have elevated MDSC levels. This was directly demonstrated by looking at the relative MDSC levels in allergic versus control patients. Monocytic MDSCs trended higher, whereas granulocytic MDSCs were increased significantly in allergic patients. Taken together, our studies indicate that MCs and MC-released histamine are critical for MDSC-mediated immune regulation, and this interaction should be taken into consideration for therapeutic interventions that target MDSCs.

[Relationships between indoor allergens, sensitization, and allergic asthma and rhinitis symptoms]

INTRODUCTION

There is a strong and consistent association between immediate hypersensitivity, asthma and exposure to allergens. However, the role that the inhaled allergen plays and the timing of events related to sensitization are still controversial.

BACKGROUND

Information obtained by studies of the follow-up of cohorts underlines the fact that there is no continuum between specific IgE responses and the development of childhood asthma. Allergic rhinitis and asthma result from a complex and multifactorial interaction between genetic factors, exposure to allergens, and many biological or chemical co-factors. However, when the child is exposed to an allergen, sensitization to the allergen is a risk factor for childhood asthma and severity of the disease.

CONCLUSIONS AND VIEWPOINTS

Despite numerous epidemiological studies, the association and links between atopy, allergens, environment, sensitization and allergic rhinitis and/or asthma remain difficult to evaluate and poorly understood. Complementary studies are also necessary for the standardization of therapeutic strategies.

Epidemiology and burden of rhinitis and rhinoconjunctivitis in 9- to 11-year-old children

BACKGROUND

Rhinoconjunctivitis (RC) is regarded as the most common chronic disease of childhood; however, the currently available epidemiological studies on prevalence, burden, and risk factors of RC are insufficient. This analysis aimed to investigate potential risk factors, symptom frequency, and burden of RC.

METHODS

Using the International Study of Asthma and Allergies in Childhood Phase II questionnaires, 6963 elementary school children aged 9-11 years were surveyed in five different city centers of Turkey. All participants were skin-prick tested with common aeroallergens.

RESULTS

The prevalence of ever rhinitis, physician-diagnosed rhinitis, current rhinitis, and current RC were 51.6, 31.0, 43.5, and 23.1%, respectively; 19.8% of children with RC symptoms were atopic to at least one allergen. Among students with RC symptoms, 42.2, 23.9, 35.8, and 28.2% reported moderate-severe interference of daily activities, at least 1 day of absence from school, visit to a health care professional, and any drug usage for rhinitis, respectively. Nasal decongestants and oral antihistamines were the most frequently used treatment. Approximately 70% of RC patients reported perennial symptoms and 42.8% were classified as mild to intermittent. Multivariate logistic regression analysis revealed family history of asthma and/or allergic rhinitis (odds ratio [OR] = 1.863; confidence interval, [CI] = 1.583-2.191; p < 0.001), living in a house with mold and dampness in the 1st year of life (OR = 1.651; CI = 1.356-2.01; p < 0.001), maternal smoking in pregnancy (OR = 1.425; CI = 1.089-1.864; p = 0.011), low monthly income (OR = 1.685; CI = 1.422-1.998; p = 0.001), current wheezing (OR = 2.543; CI = 2.151-3.006; p = 0.001), and current atopic eczema (OR = 2.503; CI = 1.96-3.196; p = 0.001) as significant risk factors for current RC.

CONCLUSION

Along with the high prevalence of RC in childhood, underdiagnosis and undertreatment of the disease are also frequent. The socioeconomic burden of the disease can be reduced by increasing awareness and proper diagnosis/treatment.

Epidemiology and burden of nasal congestion

Nasal congestion, which may be described as fullness, obstruction, reduced airflow, or being "stuffed up," is a commonly encountered symptom in clinical practice. Systematic study of congestion has largely considered it as a component of a disease state. Conditions associated with congestion include nasal polyposis, obstructive sleep apnea, and anatomic variation; however, most information on the burden of congestion comes from studies of allergic rhinitis and rhinosinusitis, diseases of which congestion is the major symptom. Congestion can be caused by other rhinologic conditions, such as non-allergic rhinitis, viral or bacterial rhinitis, and vasomotor rhinitis. Allergic rhinitis affects as much as one quarter of the population worldwide and imposes a significant economic burden. Additionally, allergic rhinitis significantly impairs quality of life; congestion causes allergic rhinitis sufferers decreased daytime productivity at work or school and reduces night-time sleep time and quality. Annually, rhinosinusitis affects tens of millions of Americans and leads to approximately $6 billion in overall health care expenditures; it has been found to be one of the most costly physical conditions for US employers. Given the high prevalence and significant social and economic burden of nasal congestion, this symptom should be a key consideration in treating patients with rhinologic disease, and there continues to be a significant unmet medical need for effective treatment options for this condition.

A review of the efficacy of desloratadine, fexofenadine, and levocetirizine in the treatment of nasal congestion in patients with allergic rhinitis

BACKGROUND

Nasal congestion is the most troublesome symptom of allergic rhinitis (AR). First-generation and older second-generation antihistamines, while effective against nasal itching, sneezing, and rhinorrhea, have limited efficacy in relieving nasal congestion.

OBJECTIVE

This review included nasal challenge studies and clinical trials that reported the effects on nasal congestion of the newer second-generation antihistamines desloratadine, fexofenadine, and levocetirizine.

METHODS

MEDLINE and EMBASE were searched for nasal challenge studies and clinical trials published in English between January 1, 1991, and January 31, 2009, using the following terms, alone or in combination: antihistamines, second-generation antihistamines, allergic rhinitis, intermittent allergic rhinitis, perennial allergic rhinitis, persistent allergic rhinitis, seasonal allergic rhinitis, nasal challenge, nasal blockage, and nasal congestion. Studies that were not active or placebo controlled, that did not evaluate change in nasal congestion scores, or that focused on treatments other than desloratadine, fexofenadine, and levocetirizine for nasal congestion associated with AR were excluded.

RESULTS

Twenty-six clinical trials met the criteria for inclusion in the review. In 11 placebo-controlled trials that included objective assessment of nasal congestion, desloratadine, fexofenadine, and levocetirizine were associated with reductions in the severity of nasal congestion through maintenance of nasal airflow. The mean AUC for nasal airflow over 6 hours was significantly greater with desloratadine compared with placebo in 3 studies (P < 0.05); placebo-controlled trials of fexofenadine and levocetirizine had similar results. In 25 placebo- and active-controlled trials that reported subject-rated symptom scores, the 3 newer antihistamines were efficacious in the treatment of nasal congestion associated with AR. In 10 trials that reported objective and/or subjective measures, desloratadine was associated with significant improvements in nasal congestion compared with placebo (P < or = 0.05), beginning as early as the first 2 hours after allergen challenge. Fexofenadine was associated with significantly lower nasal congestion scores compared with placebo in 4 studies (P <- 0.05); nasal congestion scores were significantly reduced with levocetirizine in 3 placebo-controlled trials (P < or = 0.005).

CONCLUSIONS

In the studies reviewed, desloratadine, fexofenadine, and levocetirizine were effective in relieving the nasal congestion associated with AR compared with placebo. This effect began as early as day 2 and was consistent and progressive throughout treatment. Desloratadine, fexofenadine, and levocetirizine are appropriate options for the treatment of nasal congestion in patients with AR.

Severe asthma and the omalizumab option

Atopic diseases and asthma are increasing at a remarkable rate on a global scale. It is now well recognized that asthma is a chronic inflammatory disease of the airways. The inflammatory process in many patients is driven by an immunoglobulin E (IgE)-dependent process. Mast cell activation and release of mediators, in response to allergen and IgE, results in a cascade response, culminating in B lymphocyte, T lymphocyte, eosinophil, fibroblast, smooth muscle cell and endothelial activation. This complex cellular interaction, release of cytokines, chemokines and growth factors and inflammatory remodeling of the airways leads to chronic asthma. A subset of patients develops severe airway disease which can be extremely morbid and even fatal. While many treatments are available for asthma, it is still a chronic and incurable disease, characterized by exacerbation, hospitalizations and associated adverse effects of medications. Omalizumab is a new option for chronic asthma that acts by binding to and inhibiting the effects of IgE, thereby interfering with one aspect of the asthma cascade reviewed earlier. This is a humanized monoclonal antibody against IgE that has been shown to have many beneficial effects in asthma. Use of omalizumab may be influenced by the cost of the medication and some reported adverse effects including the rare possibility of anaphylaxis. When used in selected cases and carefully, omalizumab provides a very important tool in disease management. It has been shown to have additional effects in urticaria, angioedema, latex allergy and food allergy, but the data is limited and the indications far from clear. In addition to decreasing exacerbations, it has a steroid sparing role and hence may decrease adverse effects in some patients on high-dose glucocorticoids. Studies have shown improvement in quality of life measures in asthma following the administration of omalizumab, but the effects on pulmonary function are surprisingly small, suggesting a disconnect between pulmonary function, exacerbations and quality of life. Anaphylaxis may occur rarely with this agent and appropriate precautions have been recommended by the Food and Drug Administration (FDA). As currently practiced and as suggested by the new asthma guidelines, this biological agent is indicated in moderate or severe persistent allergic asthma (steps 5 and 6).

Management of asthma with anti-immunoglobulin E: a review of clinical trials of omalizumab

Immunoglobulin E (IgE) is a key mediator of the inflammatory reactions that are central to the pathogenesis of allergic diseases such as asthma and rhinitis. The recognition of the importance of IgE in allergic disease led to the development of omalizumab, a humanized monoclonal anti-IgE antibody that binds free circulating IgE and prevents the interaction between IgE and high-affinity (FcepsilonRI) and low-affinity (FcepsilonRII) IgE receptors on inflammatory cells. By removing free IgE, omalizumab also markedly downregulates the expression of high-affinity receptors on basophils, mast cells and dendritic cells. Several studies have shown that omalizumab effectively reduces the risk of exacerbations and hospitalization and improves symptom control, lung function and quality of life in patients with severe persistent allergic asthma. Importantly, omalizumab has been shown to be effective in patients with poorly controlled severe persistent allergic asthma, a group of patients with few effective additional treatment options. In addition, omalizumab has been shown to provide effective relief from the symptoms of allergic rhinitis (including patients with concomitant asthma). Patients with uncontrolled severe persistent allergic asthma are a challenging and difficult-to-treat population for whom omalizumab might represent an important new treatment option. In addition, omalizumab may provide a means to address comorbid allergic disease in patients with asthma. Further investigation is also warranted to explore potential applications of omalizumab in occupational asthma.

Randomized, double-blind, placebo-controlled study of montelukast for treating perennial allergic rhinitis

BACKGROUND

Perennial allergic rhinitis (PAR) is a persistent allergic inflammation of the upper respiratory tract due to year-round allergen exposure.

OBJECTIVE

To evaluate the leukotriene receptor antagonist montelukast for the treatment of PAR.

METHODS

Protocol 265 was a 2-arm study performed during the winter. After a placebo run-in period, adults with perennial allergen sensitivity and active symptoms of PAR were randomized to receive 10 mg of montelukast (n=1002) or placebo (n=990) once daily during a 6-week, double-blind, active-treatment period. The primary end point was the daytime nasal symptoms score, defined as the average of scores for nasal congestion, rhinorrhea, and sneezing rated daily by patients.

RESULTS

Statistically significant improvements in PAR symptoms were seen in patients treated with montelukast. Their daytime nasal symptoms scores were reduced during treatment compared with those of the placebo group: the difference between treatments in least squares mean change from baseline was -0.08 (95% confidence interval [CI], -0.12 to -0.04; P < .001). Montelukast treatment also improved global evaluations of allergic rhinitis by patients and Rhinoconjunctivitis Quality of Life Questionnaire scores: differences vs the placebo group were -0.15 (95% CI, -0.27 to -0.04; P < .01) and -0.15 (95% CI, -0.24 to -0.06; P < .001), respectively. Other end points that showed statistically significant improvement with montelukast treatment were nighttime symptoms and each of the 4 nasal symptoms (congestion, rhinorrhea, sneezing, and itching). The treatment effects of montelukast were stable and persistent during the entire 6 weeks of treatment.

CONCLUSION

Montelukast provided statistically significant relief of PAR symptoms during 6 weeks of treatment.

A new paradigm for immunoglobulin E in allergic diseases

Recent observations at the level of the antigen presenting cell, as well as the T cell, point toward a pivotal role for interleukin (IL)-10 in the control of immunoglobulin E (IgE)-mediated allergic diseases, such as asthma and rhinitis. This has led to restructuring of the Th1/Th2 paradigm with IL-10 acting to modulate Th2-driven IgE antibody (Ab) responses. The modified Th2 response to cat allergen is associated with high-dose allergen exposure and the presence of high titer IgG and IgG4 Ab; however, IgE Ab and allergic symptoms are absent. Characteristics of this immune response indicate that it is a variant of the allergic response, which develops in an IL-10-dependent manner, but it is distinct from other types of nonallergic or tolerant responses. These observations point toward a new paradigm for the development of IgE-mediated responses. This may be important for advancing our understanding of the response to immunotherapy and anti-IgE, and for defining immune mechanisms that drive allergic responses.

Allergic rhinoconjunctivitis: epidemiology

Allergic rhinoconjunctivitis has been studied much less frequently than asthma using epidemiologic approaches. Population-based studies are difficult to conduct because of misclassification arising from the reliance on self-reported questionnaires that use terms such as allergic rhinitis or hay fever to establish the diagnosis. In addition, many epidemiologic studies focus on diagnostic skin testing or allergen-specific IgE antibodies (RASTs) as an objective outcome to assess for hay fever. These techniques are helpful but not perfect measures for predicting hay fever outcomes in epidemiologic studies. It is generally accepted, however, that allergic rhinoconjunctivitis is one of the most common of chronic diseases and is the most common atopic disorder. This article reviews the definition of allergic rhinoconjunctivitis, the epidemiology of this disorder from infancy into adulthood, and environmental risk factors for development of sensitization to certain allergens.