MOLECULAR POLYMORPHISMS OF HOUSE DUST MITE ALLERGENS

Previous studies from this laboratory have described the primary amino acid sequences of the group I and group II allergens from Dermatophagoides pteronyssinus and D. farinae. This report concentrates on polymorphisms of allergens within a species. Firstly, four cDNA clones of Der fII produced by polymerase chain reaction have been sequenced and are compared to the sequences published previously by ourselves and others. Although the sequences come from different sources, Australia and Japan, the overriding conclusion is one of similarity, with only two possible non-conservative changes in the six sequences. The nucleotides were also very conserved including the 3' untranslated regions, although some non-coding differences could be found which may provide a genetic marker. Experiments are reported to help define the group III D. pteronyssinus allergens. Previous studies have characterised the group III of D. farinae as a Mr 29-kDa molecule which can be defined by monoclonal antibodies. A Mr 17-kDa molecule of D. pteronyssinus has been reported with an almost identical N-terminal sequence. Here it is described that Der fIII isolated from different preparations of spent mite media by affinity chromatography have predominantly Mr 32-, 28- and 21-kDa forms which vary in degree from batch to batch. 83% of adults and 38% of children react with the preparation by radioimmune dot-blot. The difference between the children and adults is statistically significant and reactivity can be to at least the 32- and 28-kDa form. Antisera produced in mice against the Der fIII react to D. pteronyssinus mite extract by Western blotting primarily to a 32-kDa moiety, but also 28- and 21-kDa forms in some extracts.