Pathogenesis-related proteins of plants as allergens.
OBJECTIVE
Many pathogenesis-related (PR) proteins from plants are allergenic. We review the evidence that PR proteins represent an increasingly important group of plant-derived allergens.


METHODS
A detailed literature search was conducted through PubMed and GenBank databases.


METHODS
All reports in PubMed and GenBank related to PR protein allergens for which at least partial amino acid sequence is known were included.


RESULTS
Production of PR proteins by plants is induced in plants by stress. Members of PR-protein groups 2, 3, 4, 5, 8, 10, and 14 have demonstrated allergenicity. PR2-, 3-, 4-, and 8-homologous allergens are represented by the latex allergens. Cross-reactivity of PR3 latex allergen, Hev b 6.02, with some fruit allergens may be a reflection of the representation of homologous PR proteins among varied plants. The expression of one of the representative PR5-homologous cedar pollen allergens, Jun a 3, is highly variable across years and geographic areas, possibly because of variable induction of this PR protein by environmental factors. PR10-homologous birch pollen allergen, Bet v 1, is structurally similar to and cross-reacts with PR10 proteins from fruits (eg, Mal d 1) which cause oral allergy syndrome. PR14 allergens (eg, Zea m 14) consist of lipid transfer proteins found in grains and fruits and are inducers of anaphylaxis.


CONCLUSIONS
PR-homologous allergens are pervasive in nature. Similarity in the amino acid sequences among members of PR proteins may be responsible for cross-reactivity among allergens from diverse plants. Induced expression of PR-homologous allergens by environmental factors may explain varying degrees of allergenicity. Man-made environmental pollutants may also alter the expression of some PR protein allergens.
Midoro-Horiuti
T
T
Department of Pediatrics, Child Health Research Center, University of Texas Medical Branch, Galveston 77555-0366, USA. tmidoro@utmb.edu
Brooks
E G
EG
Goldblum
R M
RM
D000485:Allergens / Q000276:immunology; D000595:Amino Acid Sequence; D003429:Cross Reactions; D004777:Environment; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology* / Q000502:physiology; D017386:Sequence Homology, Amino Acid
D000485:Allergens; D010940:Plant Proteins; C053376:pathogenesis-related proteins, plant