Hevein-like protein domains as a possible cause for allergen cross-reactivity between latex and banana.
BACKGROUND
Patients allergic to natural rubber latex (NRL) frequently exhibit immediate hypersensitivity reactions to banana, but the molecular basis of these putative cross-reactions is unknown.


OBJECTIVE
We wanted to examine whether proteins resembling hevein, a major NRL allergen, exist in banana and whether coexisting allergy to NRL and banana can be explained by IgE cross-reactivity to these proteins.


METHODS
Allergens in banana cross-reacting with hevein were identified by IgE immunoblot inhibition. The cross-reacting proteins were purified by reversed-phase chromatography and characterized by amino acid sequencing. Allergen cross-reactivity was further assessed by IgE ELISA, IgE ELISA inhibition, and skin prick testing.


RESULTS
In immunoblotting, 9 of 15 sera from patients allergic to NRL with IgE to hevein showed IgE binding to 32- and 33-kd banana proteins. These 2 protein bands were also targets to IgG from a hevein-immunized rabbit. IgE binding to both 32- and 33-kd protein bands was totally inhibited by hevein (10 ng/mL) in all 5 sera from patients allergic to NRL sera studied. N-terminal sequencing of the purified 32- and 33-kd proteins revealed 80% identity to the N-terminus of hevein. An internal peptide (19 amino acids) of the 33-kd protein gave over 90% identity to endochitinases of several plants. In ELISA all 15 sera from patients allergic to NRL had IgE to the purified 32-kd banana protein. In ELISA inhibition hevein (10 ng/mL) inhibited approximately 50% of IgE binding to the solid-phase 32-kd banana protein in a pool of sera from patients allergic to NRL.


CONCLUSIONS
These results suggest that the commonly occurring hypersensitivity to banana in patients allergic to NRL could be explained by cross-reacting IgE antibodies binding to epitopes in hevein and in a hevein-like domain of a previously undescribed endochitinase in banana.
Mikkola
J H
JH
National Public Health Institute, Institute of Occupational Health, Helsinki, Finland.
Alenius
H
H
Kalkkinen
N
N
Turjanmaa
K
K
Palosuo
T
T
Reunala
T
T
D000328:Adult; D000485:Allergens / Q000276:immunology* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D002648:Child; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism; D007840:Latex / Q000276:immunology*; D020315:Latex Hypersensitivity / Q000276:immunology; D037102:Lectins / Q000276:immunology*; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology* / Q000302:isolation & purification; D037121:Plant Lectins; D010940:Plant Proteins / Q000276:immunology*; D011485:Protein Binding / Q000276:immunology; D011817:Rabbits; D012882:Skin Tests; D019862:Zingiberales / Q000276:immunology*
D000485:Allergens; D023181:Antimicrobial Cationic Peptides; D007840:Latex; D037102:Lectins; D010446:Peptide Fragments; D037121:Plant Lectins; D010940:Plant Proteins; C045875:hevein; D007073:Immunoglobulin E