The use of a reference allergenic extract in the evaluation of allergen products

Two commercially available mugwort (Artemisia vulgaris (Av] pollen extracts Av-ALK and Av-PS were compared with a dialysed reference mugwort pollen extract (Av-REF) by means of crossed immunoelectrophoresis (CIE), crossed radio immunoelectrophoresis (CRIE), RAST-inhibition, RAST-screening and skin prick test. Av-ALK and Av-PS both contained approximately half the number of precipitation arcs detectable in Av-REF, and Av-PS seemed to lack two intermediate allergens and two minor allergens, while Av-ALK seemed to lack one minor allergen. The RAST-inhibition curve obtained for Av-PS did not parallel the curves obtained for Av-ALK and Av-REF, indicating that the allergen composition of Av-PS differs from that of the others. Further, RAST-screening experiments support the CIE observation that Av-PS seemed to lack two of the intermediate allergens. The HEP values determined for Av-ALK and Av-PS diverge considerably from those stated by the manufacturers. The results obtained demonstrate that the outcome of a comparison between a reference allergenic extract and allergenic products depends very much on the method employed.