Seasonal levels of the major American cockroach allergen per a 9 (arginine kinase) in Bangkok and their rele-vance for disease severity.

Monitoring the levels of cockroach (CR) allergen in the environment has medical relevance as a clear dose response relationship between CR allergen exposure, sensitization and hospitalization has been reported. In this study, a cross-sectional survey of the levels of a major American cockroach (Periplaneta americana) allergen, i.e. Per a 9 (arginine kinase) in dust samples collected in various seasons throughout the year 2007 from 76 houses of CR allergic Thai patients in the Bangkok metropolitan area were determined. A monoclonal antibody-polyclonal antibody (MAb-PAb) based-sandwich ELISA was used. The MAb was specific to Per a 9 and the PAb was raised in a rabbit against the crude extract of P. americana. The detection limit of the assay was 122 pg of the allergen or 0.024 μg per gram of fine dust powder. The concentrations of Per a 9 were found to be highest during the winter months and lowest in summer. The levels of this CR allergen had a direct correlation with disease exac-erbation; i.e. the majority of the CR allergic patients had their most severe clinical manifestations during winter. Moreover, the CR allergen levels were found to be higher in wood based-houses than in concrete houses.