Skin testing in hospital

Screening for IgE-mediated allergy

Sera from 425 patients were analysed with Phadebas RAST reagents against a panel of 19 allergens and the most commonly positive results were to grass pollen, Dermatophagoides pteronyssinus and cat epithelium. Of the 275 sera RAST-positive to any allergen, 261 were positive by a RAST technique which used a mixture of the three most common U.K. allergens; the remainder were usually positive to a mould. We conclude that 1) when a positive result is obtained after screening by the mixed-allergen RAST and a representative mould RAST, then other positive RAST results are possible, but that the extent of the investigation can be guided by a knowledge of the total serum IgE level and a computer-based history analysis; 2) when a mixed-allergen RAST and a representative mould RAST is negative, then a more specified RAST including all 19 allergens used in this investigation will be negative; 3) a positive mixed-allergen RAST result is likely to be associated with a total serum IgE level over 40 U/ml and a positive symptom pattern score derived from the computer-based history analysis.

RAST atopy screen

A single in vitro screening test for atopic allergy is described. It uses the radioallergosorbent test (RAST) principle, and has been applied to screening sera from U.K. patients with possible atopic symptoms. When compared with the Phadebas RAST, the test sensitivity was 97% and the specificity 100%, and these results suggest that it is useful in any preliminary allergy investigation.