Analysis of allergenic components of Bermuda grass pollen by monoclonal antibodies

Abstract

A panel of 16 monoclonal antibodies (MoAbs) directed against Bermuda grass (Cynodon dactylon) pollen (BGP) were generated for identification and purification of the major allergenic components of the eliciting antigen (Ag). Radioimmunoprecipitation (RIP) analysis revealed that there were at least eight antigenic components with molecular weights (MW) ranging from 12 kilodalton (12 kDa) to 200 kDa. Each of these components has distinct biochemical characteristics based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). Among them, Cyn d Bd67K and Cyn d Bd58K were basic proteins, Cyn d Bd35K consisted of at least four isomeric components with isoelectric points ranging from 6.2 to 7.2. The other antigens (Cyn d Bd68K, 48K, 38K, Cyn d Bd200K, Cyn d Bd46K, Cyn d Bd25K and Cyn d Bd12K) were all acidic proteins. The IgE binding capacity of all these antigens was determined with sera from 11 BGP-allergics by using a modified radioallergosorbent test. All but one of the antigens (Cyn d Bd200K) were found to react with human IgE from sera of BGP-allergic patients. Among those human IgE-binding molecules, Cyn d Bd35K reacted with allergic sera most frequently (10 of 11), followed by Cyn d Bd58K (8 of 11) and Cyn d Bd46K (7 of 11) respectively. Our results suggest that Cyn d Bd35K, Cyn d Bd58K, and Cyn d Bd46K are major allergens of BGP, and the MoAbs we obtained should be valuable tools for further purification of these allergens.