[A study of skin test with regard to age differences and agreement with positive results from the RAST and ELISA...

Skin tests of the scratch type were performed on 132 asthmatic patients with 28 allergens. The threshold titers of skin test, RAST and ELISA of house dust, HD mites, Japanese cedar pollen, ragweed pollen and orchard grass pollen were included. The main skin-positive allergens among the patients were as follows: house dust, HD mites, Japanese cedar pollen, orchard grass pollen, timothy grass pollen and ragweed pollen. There are age differences on skin-positive rates among 4 age groups of the patients; 90% of the patients under 40 years old groups reacted positively to any of 28 allergens, while half number of the patients groups over 40 years old reacted positively to the allergens. According to the quantitative analysis between threshold titers of skin test and RAST titers using house dust and HD mites allergens, specific IgE production shall be decreased in the patients over 40 years old. Using 5 main allergens above mentioned, the agreements of positive responses between three methods were compared. RAST positive responses correlated well with the skin test results, while ELISA positive responses correlated rather poorly with the skin test results. However, correlation between RAST and ELISA results was relatively good. The correlation of positive responses to house dust and HD mites by the three methods was very good, but there were some cases where positive responses were obtained by only one of the methods.