IMMUNOBLOTTING ANALYSIS OF TWIN SERA PROVIDES EVIDENCE FOR LIMITED GENETIC-CONTROL OF SPECIFIC IGE TO HOUSE-DUST MITE ALLERGENS

Background: Although some studies have shown genetic control of specif ic IgE responses to purified grass allergens, studies with other aller gens have not supported this. The extent of such control for house dus t mite (HDM) (Dermatophagoides pteronyssinus) allergens is unclear. Ob jective: We sought to determine the extent to which genetic factors co ntrol the specificity of IgE responses to individual HDM allergens by comparing the immunoblot patterns of IgE binding of serum from monozyg otic and dizygotic members of a large cohort of Australian twins. Meth ods: HDM proteins separated by sodium dodecylsulfate-polyacrylamide ge l electrophoresis were immunoblotted with sera from 317 twin pairs in which at least one twin had at least a weak HDM skin test response. Co ncordance levels for IgE binding to the individual HDM components were compared in the subset of 142 pairs of twins in which both twins were allergic to HDMs (skin prick test wheal diameter, > 3 mm). Results: O ver all 36 blotted bands, the mean case-wise concordance was 41% for m onozygotic twins and 17% for dizygotic twins. Of the components detect ed, only those of molecular weights 23 kd and 16 lid mere significantl y different between the groups (p < 0.01). Differences observed betwee n the monozygotic and dizygotic twins could be partly explained by ove rall IgE hyperresponsiveness. Conclusion: Evidence for genetic control of IgE responses to 36 IgE-binding HDM components from a large sample of twins showed significant differences in concordance for two compon ents and nonsignificant differences for several others. In the monozyg otic twins, concordance never exceeded 67% for any band, and most mono zygotic individuals recognized components their co-twin did not. Genet ic control of overall atopy in monozygotic twins is far stronger than that controlling specific sensitization to HDM allergens.