Determination of T and B Cell Epitopes of Aspergillus fumigatus Ribotoxin and Heat Shock Protein.

Ribotoxin Asp f1 and heat shock protein Asp hsp1 from Aspergillus fumigatus represent the major components of A. fumigatus allergic complex. Eight computer predicted peptides corresponding to probable T epitopes of Asp f1 (4 peptides) and Asp hsp1 (4 peptides) have been synthesized according to the primary sequence of the proteins. The peptides Asp f1 15-27, 87-99 and Asp hsp 84-96, able to bind high affinity sera from mice BALB/c immunized with crude A. fumigatus extract, were considered to represent B cell epitopes. To screen T cell epitopes among the peptides splenocytes from mice immunized with crude A. fumigatus extract were stimulated in vitro with A. fumigatus or peptides, and their Ab production was analyzed. Spontaneous A. fumigatus-specific Ab production was found in unstimulated control. In cultures stimulated with 20 &mgr;g/ml of A. fumigatus preparation Ab production was blocked by 92%. The peptide Asp f1 87-99 decreased synthesis of A. fumigatus-specific Abs by 80%. The peptide Asp f1 15-27 and those overlapping hsp1 18-31 and 22-36 induced 34-37% decrease in Ab production. Other A. fumigatus-derived or irrelevant peptides did not affect specific Ab production. Thus, these peptides, containing T cell epitope, may be considered as potential candidates for peptide-based immunotherapy of allergic aspergillosis.