COCKROACH ALLERGENS--IMMUNOCHEMISTRY & ALLERGIC DISEASE

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Increasing evidence suggests that cockroach (CR) sensitization is an important cause of asthma, particularly among African-Americans living in urban areas in CR infested housing. The aims of the present proposal are to identify, purify and sequence major allergens from the two most common indoor CR species, Blattella germanica and Periplaneta americana. Murine monoclonal antibodies (mAb) will be raised against CR extracts and screened to identify antigens recognized by human IgE antibodies. Selected mAb will be used together with biochemical techniques to purify CR allergen(s). Recombinant DNA techniques will be used to determine the complete nucleotide sequences of major CR allergens. The sequences will be obtained either from polymerase chain reaction (PCR) amplification products or from CR cDNA clones, which will be identified using oligonucleotide probes, mAb or IgE antibodies. PCR products or cDNA clones will be sub-cloned and sequenced by dideoxy sequencing. Allergen encoding cDNA will be cloned into bacterial vectors to facilitate high level expression of recombinant allergens. These studies will determine the structural and antigenic relationships between allergens produced by different CR species. Sequence similarity searches will be used to investigate the biologic function of CR allergens and immunocytochemical techniques will be used to localize sites of allergen production in CR tissues. MAb based immunoassays will be used to measure indoor CR allergen levels in dust and air samples from the houses of patients with asthma and in those of non-asthmatic controls. Preliminary studies have been carried out in Charlottesville VA, Atlanta GA and Wilmington DE. The proposed studies will investigate the sites of allergen accumulation in the home and the particle size and concentration of airborne allergen. The aim will be to establish the form in which CR allergens cause sensitization for IgE antibody responses and to define threshold levels of exposure that are risk factors for both sensitization and exacerbations of allergic disease. The assays will be used to investigate whether methods to control CR infestation can cause reductions in CR allergen levels. These studies would help establish the feasibility of using CR control in the management of asthma. The proposed studies are designed to improve understanding of a group of allergens that appear to be an important cause of asthma, particularly among those minority populations that are most affected by the recent increases in mortality and morbidity from this disease.