USING MONOCLONAL-ANTIBODIES TO CHARACTERIZE A SEQUENTIAL EPITOPE ON THE GROUP-I ALLERGEN OF BERMUDA GRASS-POLLEN

Background: Cyn d 1, the group I allergen of Bermuda grass pollen, had been purified and characterized. Methods: A sequential B cell epitope on Cyn d 1 was studied with monoclonal antibodies (MoAbs). Cyn d 1 wa s cleaved by Achromobacter protease I into fragments, and the resultin g peptides were fractionated on reversed-phase columns before being re acted with anti-Cyn d 1 MoAbs in a radioimmunoassay. A Cyn d 1 fragmen t recognized by its MoAb was selected for Edman degradation. A synthet ic peptide was constructed according to the determined sequence. Resul ts: The epitope on Cyn d 1 recognized by MoAb 18-53 was found to be co nformation independent, since its activity was not changed after sodiu m periodate, guanidine or urea treatment. The enzyme-cleaved fragment containing this epitope was determined to be DVDKPPFDGMTACGNEPIF which corresponds to the N-terminal 46-64 residues of Cyn d 1. The presence of this sequence in the epitope recognized by MoAb 18-53 was demonstr ated by enzyme immunoassay and further confirmed by inhibition of bind ing enzyme immunoassay with synthetic peptides, Some cross-reactivity with the N-terminal 45-63 residues of Lol p 1 was also found. Conclusi ons: The primary structure of a sequential epitope on Cyn d 1 was dete rmined, and its activity was confirmed with peptides synthesized accor ding to the determined sequence.