SPECIFIC HYPOSENSITIZATION IN PATIENTS ALLERGIC TO PARIETARIA-OFFICINALIS POLLEN ALLERGEN

The effects of specific hyposensitization in 40 patients with Parietar ia officinalis-sensitive seasonal rhinoconjunctivitis were studied dur ing three years of treatment. The patients were treated with subcutane ous injections of a new, partially purified, characterized and standar dized pollen extract of P. officinalis allergen (alum-absorbed depot p reparation). Treatment was applied from November to mid March and it w as clinically assessed during the plant flowering season (mid March to end of June). Laboratory tests were performed yearly when beginning a nd ending treatment. Serum concentrations of P. officinalis pollen all ergen-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 tho se 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 yea r 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%), whe reas the size of skin test reaction and the percentage of eosinophils among white blood cells remained unchanged. Clinically, both symptom a nd additional medication scores significantly decreased in the treated patients in the second (symptom score 3.4 +/- 2.3; additional medicat ion score 2.1 +/- 1.7) and third (symptom score 2.1 +/- 1.7; additiona l medication score 1.4 +/- 0.8) year as compared to their own referenc e 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 addit ional medication score. These scores were also significantly lower tha n in patients treated with ketotifen.