Allergens in 1998: from molecular biology to improved patient care

Desensitization effect of preseasonal seven-injection allergoid immunotherapy with olive pollen on basophil activation: the efficacy of olive pollen-specific preseasonal allergoid immunotherapy on basophils

BACKGROUND

It has previously been demonstrated that subcutaneous immunotherapy with allergoids positively affects clinical and immunological parameters even after 7 preseasonal injections. However, its effect on basophil activation remains unclear. We investigated the effect of preseasonal allergoid immunotherapy on basophils and concomitantly assessed its clinical and immunological efficacy in olive pollen-monosensitized patients.

METHODS

This study enrolled 437 consecutive patients with respiratory allergy and positive skin prick tests (SPTs); 212 (48.5%) patients were sensitized to olive pollen, and 33 (7.5%) patients were sensitized to olive pollen only. Of these patients, 23 received preseasonal immunotherapy with an olive pollen allergoid. The olive pollen-specific basophil activation, the titrated nasal provocation test, the nasal symptom score, and olive pollen-specific IgE, IgG1 and IgG4 levels were evaluated before immunotherapy and 8 months after the end of immunotherapy in the follow-up visit.

RESULTS

In comparison to baseline evaluation, 7 preseasonal injections of an allergoid resulted in a significant decrease in the percentage of basophils expressing CD63 (29 vs. 7%, respectively, p < 0.0001) and a significant increase in the titrated nasal provocative dose (1/10 vs. 1/1, respectively, p < 0.01). SPT induration diameters caused by an olive pollen extract decreased (12 mm at baseline vs. 5.5 mm at follow-up, p < 0.005), as did nasal symptom score (7 at baseline vs. 3 at follow-up, p < 0.01). Olive pollen-specific IgE (17.5 vs. 50 kU/l, p < 0.012), IgG1 (0.16 vs. 2.9 µg/ml, p < 0.0001) and IgG4 (0.07 vs. 1.92 µg/ml, p < 0.0001) levels significantly increased.

CONCLUSIONS

Immunotherapy with 7 preseasonal injections of an olive pollen allergoid decreases olive pollen-specific basophil activation over 8 months, an effect observed in vitro and in vivo.

Human allergy to environmental pet danders: a public health perspective

The prevalence of human allergy to pet danders has increased rapidly over the past six decades, as a consequence of lifestyle changes that have enhanced ambient exposure to pet allergens. This is a problem of global public health importance, as the morbidity associated with allergic diseases disproportionately affects socio-economically disadvantaged populations, particularly children. Although the public often seeks advice from veterinary health-care professionals regarding healthy pet ownership practices, including strategies for reducing residential pet dander exposure, many misconceptions persist in the public domain regarding pet dander allergy, such as the belief that certain dog and cat breeds are 'hypoallergenic' due to their hair/coat type. This review considers the epidemiology of human exposure to the major cat and dog dander allergens, Fel d 1 and Can f 1 respectively, and the sensitization mechanisms to them, including the hygiene hypothesis and the putative role of bacterial endotoxin. The literature regarding primary and secondary exposures in different ambient environments is explored including threshold effects that influence allergen sensitization and elicitation of symptoms, and environmental intervention strategies that seek to reduce allergen exposure. Pet-specific factors, including the aetiopathogenesis of the several cat and dog allergens that have been characterized to the molecular level, individual animal characteristics that influence Fel d 1 and Can f 1 shedding, and pet-directed interventions intended to reduce allergen dispersal, are discussed.

Allergen immunotherapy in the prevention of asthma

PURPOSE OF REVIEW

Asthma is a disease causing significant morbidity and mortality. In the recent past, there has been an explosion of pharmacotherapeutic options attempting to control the disease. Unfortunately, none of the current options offers the promise of prevention or a permanent cure. However, there appear to be exciting, new data emerging to support the hypothesis that the prevention or early treatment of allergic rhinitis, such as with the use of allergen immunotherapy, may help mitigate the severity of bronchial symptoms and even prevent the development of asthma. In this paper, we review recent research published proposing immunotherapy as a means of preventing the development of, or at least ameliorating, allergic asthma.

RECENT FINDINGS

There is evidence that the upper and lower airways may be considered a single unit, with the nasal and bronchial mucosa having features in common. Epidemiological, pathophysiological and clinical studies have shown that they can be affected by similar inflammatory triggers, with interconnected mechanisms amplifying the inflammatory cascade. Allergic rhinitis is interrelated to, and is a risk factor for, the development of asthma. An evidence-based review validates the successful use of allergen immunotherapy in treating allergic rhinitis and asthma. There is promising evidence advocating its use in the prevention of clinical asthma.

SUMMARY

This article explores current research pertaining to the use of immunomodulation, such as by using allergen immunotherapy, to ameliorate and prevent the development of allergic asthma.