COMPARISON OF PHARMACIA IGE-EIA AND PHADEBAS-RAST WITH PHARMACIA CAP-SYSTEM-FEIA IN THE DETERMINATION OF TOTAL AND SPECIFIC IGE

The determination of total and allergen-specific IgE are well established methods in allergy diagnosis. The Pharmacia CAP (capsulated hydrophilic carrier polymer) system has a new solid phase which leads to advantages in comparison to the conventional Radio-Allergo-Sorbent-Test (RAST) according to a more rapid and increased protein binding. In 268 cases total IgE was determined by enzym-immuno-assay (Pharmacia IgE EIA) and CAP. There were more samples (214/268) with higher results in the determination of total IgE by the CAP system. This trend was not reflected in the arithmetic mean value. The variation analysis was in favour of the enzym-immuno-assay technique. We studied RAST and CAP system in fivefold determinations of 105 serum probes for intra- and inter-assay variance to aeroallergens (grass and birch pollen, D. pter., D. far., cat epithelium), food allergens (egg and milk protein) and hymenoptera venoms. RAST and CAP system correlated well (r = 0.91). For most of the tested allergens the CAP system showed higher results. This led to a classification which was in the average 0.46 (class 0-4), i.e. 0.66 (class 0-6) classes higher. According to lower variations of the single results the mean variation coefficient (vc) of the CAP system (intra-tests) was significantly lower (7.57) than the vc of the RAST. Two cases (cat epithelium, hen's egg white), giving positive results in the RAST and negative in the CAP and nine cases (hymenoptera venom 7, D. far. 2) with deviating positive results in CAP were discordantly assessed. In this study the CAP system showed higher values of specific IgE-antibodies with a better reproducibility compared to the RAST. This was not true for all tested allergens in the same way. The CAP system offers additional technical advantages with regard to practicability.