Common German cockroach whole body and fecal allergens: immunoprint inhibition studies

Previous studies have established that cockroach allergens are important sensitizing agents in the induction/exacerbation of urban asthma. The present investigation compared saline extracts of German cockroach (Blattella germanica) whole bodies (GWBE) and feces (GFE) as important sources of allergens. Both extracts were tested prior to or following gel filtration on Sephadex G-75 (Fr2). Immunoprinting of unfractionated fecal extract using 10 RAST-positive sera detected a series of allergens with pI values between 4.15-4.55 and a single allergen that focused near the cathode. Multiple allergens were detected in both GWBE-Fr2 and GFE-Fr2. Generally, most RAST-positive sera reacted similarly, although GWBE-Fr2 had more allergenic proteins than GFE-Fr2 with pI less than 4.7 and fewer allergens with pI greater than 4.7. Immunoprint inhibition of GWBE and GFE by GWBE and GFE also demonstrated allergenic similarity, although homologous extracts were more effective inhibitors than heterologous preparations. Collectively, these studies demonstrate the allergenic similarities of cockroach whole body and fecal extracts. Thus fecal material may provide an important source of sensitizing antigen.