International Immunology, Vol. 14, No. 9, pp. 993-1001,
September 2002
© 2002 Japanese Society for Immunology
Molecular and structural analysis of the panallergen profilin B cell epitopes defined by monoclonal antibodies
1 Research and Development Department, Bial-Arístegui, Alameda Urquijo 27, 48008 Bilbao, Spain 2 Proteins Design Group, National Center of Biotechnology–CSIC, 28049 Madrid, Spain
Correspondence to: J. A. Asturias; E-mail: la.lp{at}bial.es.
Transmitting editor: C. Martínez-A
Interactions of five mouse mAb (10A4, 5F2, 9A7, 9G4 and 3H8) and sunflower profilin were characterized using synthetic overlapping peptides. All the continuous B cell epitopes analyzed in this work were 6–10 amino acids in length, and clustered at the N- and C-terminal 
-helices and a two-stranded segment composed of residues 40–50. Mutational analysis of the epitopes revealed that single amino acid changes within these peptides had dramatic effects on IgG-binding characteristics. A three-dimensional molecular model of sunflower profilin was generated by homology modeling based on the crystal structure of Arabidopsis thaliana profilin. All but one of the murine B cell epitopes defined in this work were located on the surface of the profilin molecule in the -helices (10A4 and 3H8) or in the turns (5F2 and 9G4). In contrast, 9A7 epitope was located in the profilin core and partially buried by the C-terminal. Two mAb (5F2 and 10A4) inhibited the binding of anti-profilin human IgE up to 52%. In contrast, mAb 3H8 seemed to enhance the binding of anti-profilin IgE of sera from allergic patients.
Keywords: allergen, continuous epitopes, IgE-binding site, sunflower, three-dimensional structure