Physiopathology of hay fever

Pollinosis is a model physio-pathology for IgE-dependent diseases. Rhinitis and conjunctivitis are the parent symptoms, with asthma a non-exceptional complication. The mechanisms are linked to an immuno-allergic inflammation; the observed differences are due to specific anatomo-physiologies of the sensitive cells. The pollen allergens are collected by the CPA and expressed after cleavage into peptides, at the surface of the CPA in association with class II HLA molecules. T-lymphocytes recognise the complex HLA-peptide molecules. Type Th2 lymphocytes produce the cytokines that the necessary for the synthesis of IgE (IL4, IL13...). At the stage of silent clinical sensitivity the precocious and delayed effector stages of immediate hypersensitivity follow. The precocious stage corresponds with degranulation of cells that express Fc epsilon R1, for release of vaso-active and lipid mediators that produce the immediate symptoms of pollinosis. The delayed phase corresponds with a flood of eosinophils, which release their toxic proteins proteins and also take part in oedema and nasal obstruction. Mucosal innervation, neurotransmitters and neuromediators also intervene in the modulation of symptoms.     

Genetic and environmental contributions to hay fever among young adult twins

BACKGROUND: The susceptibility to develop hay fever is putatively the result both of genetic and environmental causes. We estimated the significance and magnitude of genetic and environmental contributions to hay fever among young adult twins. METHODS: From the birth cohorts 1953-82 of The Danish Twin Registry 11,750 twin pairs were identified through a nationwide questionnaire survey. Subjects were regarded hay fever cases when responding affirmatively to the question 'Do you have, or have you ever had hay fever?' Latent factor models of genetic and environmental effects were fitted to the observed data using maximum likelihood methods. RESULTS: The overall cumulative prevalence of hay fever was 12.6%. Identical twins were significantly more likely to be concordant for hay fever than were fraternal twins (P<0.001). Additive genetic effects accounted for 71% and non-shared environmental effects accounted for 29% of the individual susceptibility to hay fever. The same genes contributed to the susceptibility to hay fever both in males and in females. In families with asthma, the susceptibility to develop hay fever was, in addition to genes, to a great extent ascribable to family environment, whereas the aetiology of 'sporadic' hay fever was mainly genetic. CONCLUSIONS: The susceptibility to develop hay fever is attributable to major genetic influences. However, effects of family environment and upbringing are also of importance in families where asthma is present. These results indicate that different sub-forms of hay fever may have different aetiologies.     

Multicenter double-blind comparative study of terfenadine and cetirizine in hay fever.

The efficacy and safety of terfenadine in the management of hay fever were compared with those of cetirizine in a multicenter, double-blind, parallel-group study, carried out during the 1990 spring pollen season. The patients were randomly assigned to one of two groups of treatment, 70 patients being given terfenadine 120 mg, and 72 patients cetirizine 10 mg, once daily for 7 days. The severity of the main symptoms was evaluated at baseline and after treatment by a 4-point rating scale. In addition, the overall symptom severity was recorded daily by the patient on a diary card. Both terfenadine and cetirizine produced significant relief of symptoms by the end of treatment, with a decrease in symptom severity ranging from 46 to 69% for terfenadine and from 40 to 55% for cetirizine. Adverse effects experienced by terfenadine- and cetirizine-treated patients were mainly drowsiness, with minor differences between the two groups. The results of this study confirmed previous experiences, showing that both terfenadine and cetirizine once daily should be regarded as effective drugs for the management of hay fever.     

Beclomethasone dipropionate aerosol treatment of hay fever. A dose-response investigation.

In a controlled, double-blind study 20 children and adults, suffering from summer hay fever, were treated intranasally with a daily dose of 200 mug, 300 mug or 400 mug beclomethasone dipropionate (Beconase, Becotide Nasal) or with placebo for 2 weeks during the hay fever season. No beneficial effect of the placebo treatment was observed. In patients treated with 200 mug and 300 mug beclomethasone dipropionate a day there was a moderate decrease in nasal symptom scores and in use of antihistamine tablets. As the results indicated 400 mug a day to have the most pronounced effect on nasal symptoms, this dosage is recommended for children as well as adults suffering from summer hay fever.     

Early farm residency and prevalence of asthma and hay fever in adults

Background: Asthma and hay fever have been found to be both positively and negatively associated with farming lifestyles in adulthood. Lack of congruency may depend upon early life exposure. Objective: To assess the importance of different periods of farm residency for asthma and hay fever in an adult Canadian population. Methods: We conducted a questionnaire survey in rural Saskatchewan, Canada. We assessed a history of asthma and hay fever with five categories of farm residency that were mutually exclusive: first year of life only, currently living on a farm, both first year of life and currently living on a farm, other farm living, and no farm living. Generalized estimating equations were used to adjust for clustering effects of adults within households. Results: Of the 7148 responding, 30.6% had an early farm living experience only, 34.4% had both early and current farm living experiences, while 17.4% had never lived on a farm. The overall prevalence of ever asthma and hay fever was 8.6% and 12.3%, respectively, and was higher in women. Sex modified the associations between ever asthma and hay fever with farm residency variables whereby women had a decreased risk for both asthma [adjusted odds ratio (OR_adj): 0.67, 95% confidence interval (CI):0.47–0.96] and hay fever (OR_adj: 0.60, 95% CI: 0.44–0.83) with an early farm exposure only. Men currently living on a farm without an early farm exposure had an increased risk for ever asthma (OR_adj: 1.82, 95% CI: 1.02–3.24). Conclusion: Farm residency in the first year of life shows a protective effect for adult asthma and hay fever that appears to differ by sex.