A further study has been made on the house dust mite extract, Dermatophagoides pteronyssinus, with emphasis on gel-filtrated fraction 2 (F2). The crude mite extract showed at least nine discs on polyacrylamide disc electrophoresis and contained less than 0.25% sialic acid and less than 0.5 mM hexosamine and no detectable uronic acid. From gel filtration of the crude extract a No 2 fraction (F2) with allergenic activity showed at least five components on SDS disc electrophoresis covering a molecular weight range of between 15,000 and 70,000. The major allergenic activity of F2 dissolved in pH 7-8 and 4-5 on an isoelectric focusing column. Affinity chromatography and lectins showed that allergenic activity did not relate to structures of N-acetyl-D-glucosamine or N-acetyl-D-galactosamine. Allergenic activity of the crude extract was no affected by peptic digestion and the mite digest prepared by trypsin and pronase showed a similar fractionation and activity profile as crude extract.

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