Purification and characterization of a major allergen from the house dust mite Dermatophagoides farinae.

A major allergen from an extract of the house dust mite, Dermatophagoides farinae, was shown to be extremely heterogenic with respect to charge. A slightly basic component of this allergen with a pI of 8, was purified by isoelectric focusing in two steps. The purified component, denoted antigen 19/20 IIa, seemed to be representative for the allergenic activity of the major allergen. The amino acid analysis suggested that antigen 19/20 IIa had a molecular weight of 9400 and contained one residue of galactosamine. SDS polyacrylamide gel electrophoresis did indicate a somewhat higher molecular weight of 14,500. Antibodies against the purified component cross-reacted with a crude extract of the mite Dermatophagoides pteronyssinus.