SPECIFIC HYPOSENSITIZATION IN PATIENTS ALLERGIC TO PARIETARIA-OFFICINALIS POLLEN ALLERGEN

The effects of specific hyposensitization in 40 patients with Parietaria officinalis-sensitive seasonal rhinoconjunctivitis were studied during three years of treatment. The patients were treated with subcutaneous injections of a new, partially purified, characterized and standardized pollen extract of P. officinalis allergen (alum-absorbed depot preparation). Treatment was applied from November to mid March and it was clinically assessed during the plant flowering season (mid March to end of June). Laboratory tests were performed yearly when beginning and ending treatment. Serum concentrations of P. officinalis pollen allergen-specific IgE antibodies decreased (first year- from 18.7 +/- 7.7 to 17.9 +/- 7.6 PRU/ml; second year: from 16.3 +/- 7.1 to 14.1 +/- 6.6 PRU/ml; third year from 12.3 +/- 5.6 to 10.9 +/- 5.6 PRU/ml) and those of specific IgG increased (first year: from 15.3 +/- 13.2 to 21.7 +/- 14.0%; second year from 28.5 +/- 13.0 to 36.3 +/- 15.9%; third year from 29.9 +/- 14.1 to 38.9 +/- 16.8%) during the treatment. Histamine release from peripheral blood leukocytes challenged in vitro with the allergen decreased during the three years of the treatment (first year from 42.3 +/- 13.0 to 33.1 +/- 10.8%; second year from 31.9 +/- 11.9 to 19.1 +/- 8.5%; thirdyear from 19.4 +/- 4.6 to 14.3 +/- 4.60%), whereas the size of skin test reaction and the percentage of eosinophils among white blood cells remained unchanged. Clinically, both symptom and additional medication scores significantly decreased in the treated patients in the second (symptom score 3.4 +/- 2.3; additional medication score 2.1 +/- 1.7) and third (symptom score 2.1 +/- 1.7; additional medication score 1.4 +/- 0.8) year as compared to their own reference values obtained in the first year of treatment (symptom score 4.7 +/- 3.6; additional medication score 2.5 +/- 1.8). Clinical improvement was found in 67.5% of patients in symptom score, and in 47.5% in additional medication score. These scores were also significantly lower than in patients treated with ketotifen.