The IgE-binding epitopes of rPar j 2, a major allergen of Parietaria judaica pollen, are heterogeneously recognized among allergic subjects.
Pollen allergens are multivalent proteins that cross-link IgE antibodies on mast or basophil cells, inducing secretion of biologic mediators, and resulting in various allergic symptoms. The IgE-binding regions of the Parietaria judaica (Pj) pollen major allergen rPar j 2 were investigated. Twenty-nine single sera from Pj-allergic subjects were tested by Western blot against five recombinant peptides. At least four putative IgE-binding epitopes were identified. The analysis of their diffusion suggested a heterogeneous IgE-binding response. In fact, 75% of the sera reacted with peptide 1-54, 48% with peptide 48-101, 24% with peptide 1-30, 7% with peptide 29-54, and none with peptide 48-76. These five peptides were analyzed with the histamine-release assay. Only peptide 48-101 was capable of inducing degranulation and release of histamine. These results suggest that the recombinant rPar j 2 allergen contains IgE epitopes that are heterogeneously recognized by sensitive patients, and that therefore the therapeutic approach based on the use of haptenic peptides needs a careful evaluation.
Costa
M A
MA
Istituto di Biologia dello Sviluppo, CNR, Palermo, Italy.
Duro
G
G
Izzo
V
V
Colombo
P
P
Mirisola
M G
MG
Locorotondo
G
G
Cocchiara
R
R
Geraci
D
D
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001666:Binding Sites, Antibody; D015153:Blotting, Western; D018985:Epitopes, B-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D010944:Plants; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D011852:Radioallergosorbent Test; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology*
D000485:Allergens; D052179:Antigens, Plant; D018985:Epitopes, B-Lymphocyte; C103299:Par j 2.0101; D010446:Peptide Fragments; D011994:Recombinant Proteins; D007073:Immunoglobulin E