Report of a meeting on allergic diseases Geneva, 24-28 July 1978

Titration of immunotherapy by periodical nasal allergic challenges in the treatment of allergic rhinitis

OBJECTIVE

To determine the benefits of nasal allergen challenge (NAC) in monitoring immunotherapy for allergic rhinitis in a clinical setting.

DESIGN

Two hundred consecutive courses of immunotherapy, with pyridine-extracted alum-precipitated allergen extracts (Allpyral), were personally carried out by the writer and analysed. Diagnosis before treatment was confirmed by NAC and the duration of treatment determined by periodical NAC.

SETTING

Consultant allergist's clinical practice.

PARTICIPANTS

Patients with allergic rhinitis who were referred for treatment; 79 patients were allergic to grass, 70 to the house dust mite, 30 to plantain and 21 to miscellaneous allergens.

RESULTS

The mean protein nitrogen units (pnu) required to reverse an NAC was 145 467 pnu for grass, 93 771 pnu for mite, 103 137 pnu for plantain, and 121 030 pnu for miscellaneous allergen patients. The range of injections to obtain conversion to a negative NAC was wide. For grass it was 9-58 injections, for mite 6-47 injections, for plantain 4-39 injections, and for miscellaneous allergens 10-79 injections. Ten grass-sensitive patients who received an average of 477 807 pnu failed to convert to a negative NAC result. Similarly, two mite-sensitive patients who received 467 370 PNU, and one plantain-sensitive patient, one cat-sensitive patient and one horse-sensitive patient, who had 389 240 pnu, 148 520 pnu and 719 540 pnu respectively, failed to convert. One patient who was very sensitive to grass pollen developed urticaria which required an injection of adrenaline.

CONCLUSION

Immunotherapy for allergic rhinitis with Allpyral is effective--as determined by the conversion of NAC results from positive to negative--providing a sufficient dose is given. The manufacturer's recommended dose is inadequate. The procedure is safe for mite, plantain and miscellaneous allergens, and only one reaction occurred with grass given in a high dosage protocol, which has subsequently been altered. Considering that the British Committee of Safety of Medicines reported no deaths from Allpyral injections, its recommendations appear over cautious for this make of extract.

Incidence of atopic disease in a tropical environment: partial independence from intestinal helminthiasis

The reported incidence of atopic disease in the tropical environment, albeit somewhat controversial, has often been very low. This has been postulated to be due to an inhibitory influence of intestinal helminthiasis, although the predominantly rural nature of the populations studied might also be an important factor to consider. We evaluated two tropical groups in Venezuela that were basically comparable, both being highly parasitized but one of which was urban and the other rural. The apparent incidence of allergic conditions in the urban group was, in fact, comparable to that in temperate countries, whereas that of the rural subjects was markedly lower. A similar difference was found in skin test positivity to common inhalant allergens, although reactivity to Ascaris extract was comparably high between the two groups, and total serum IgE and eosinophil levels were uniformly elevated. Our results suggest that the incidence of atopic disease in the topical environment may depend not only on the intensity of helminthiasis suffered but also on factors related to the urban-rural situation.