Comparison of allergenic potency of five batches ofAlternaria alternata for preparation of reference standard

Five batches of 34-016 isolate were grown separately on synthetic revised tobacco medium for 28 days. Extracts of the mycelia were prepared and their biochemical and immunological properties were examined. The extracts had similar isoelectric focussing (IEF) patterns. In crossed-radioimmuno-electrophoresis (CRIE) using human atopic sera, each showed two dominant and two to three minor allergens. In direct radioallergosorbent (RAST) and RAST inhibition tests with human atopic sera and passive cutaneous anaphylaxis (PCA) tests with mouse IgE, all samples were of similar potency. In IgE immunoblots of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gels, each extract showed strongly reactive bands at 16, 18, 30, 33 and 59–100 kDa MW. These results indicate that a reference preparation ofA. alternata suitable for standardization purposes can be obtained from any batch of 34-016 isolate.