Allergenicity and immunogenicity of the major mugwort pollen allergen Art v 1 chemically modified by acetylation.
BACKGROUND
Treating allergies with modified allergens is an approach to make the treatment safer and more efficient. Art v 1 is the most prominent allergen of mugwort pollen and a significant cause of hayfever around Europe. The aim of this study was to reduce the allergenicity of Art v 1 by acetylation, and to investigate the capacity of the modified protein to generate blocking antibodies.


METHODS
The reduction of allergenicity of Art v 1 following acetylation was monitored by immunoblot, ELISA inhibition using a pool of sera from mugwort pollen allergic patients, basophil activation assay and by skin prick testing of mugwort-allergic patients. Rabbits were immunized against Art v 1 and acetylated Art v 1 (acArt v 1) and the rabbit antisera were tested for their capacity to block human IgE binding in ELISA. Human T cell proliferation against Art v 1 and acArt v 1 was examined in peripheral blood mononuclear cells (PBMCs) of mugwort pollen allergic patients and cytokine release in PBMC cultures was monitored.


RESULTS
Acetylation of Art v 1 gave a derivative of reduced allergenicity in the in vitro and ex vivo tests applied. The skin test reactivity to acArt v 1 was significantly reduced in 19 patients when compared with the reactivity to Art v 1. Rabbit antibodies to acArt v 1 and Art v 1 showed similar capacity to block human IgE binding to Art v 1 in inhibition ELISA. Both proteins were able to induce proliferation of PBMCs and CD3/CD4(+) cells of mugwort-allergic patients. Release of IL-5 was significantly reduced in cultures stimulated with acArt v 1.


CONCLUSIONS
Art v 1 modified by acetylation had a significantly reduced allergenicity in vitro and in vivo, while its immunogenicity was retained. Modification of allergens by acetylation could be a new strategy for allergen-specific immunotherapy.
Perovic
I
I
Faculty of Chemistry, Department of Biochemistry, University of Belgrade, Studentski trg 16, Belgrade, Serbia.
Milovanovic
M
M
Stanic
D
D
Burazer
L
L
Petrovic
D
D
Milcic-Matic
N
N
Gafvelin
G
G
van Hage
M
M
Jankov
R
R
Cirkovic Velickovic
T
T
D000107:Acetylation; D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000737:chemistry* / Q000276:immunology*; D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D000937:Antigen-Antibody Reactions / Q000276:immunology; D052179:Antigens, Plant; D015549:Basophil Degranulation Test; D001491:Basophils / Q000276:immunology; D001667:Binding, Competitive / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D007114:Immunization; D007073:Immunoglobulin E / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007526:Isoelectric Point; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry* / Q000276:immunology*; D011058:Pollen / Q000737:chemistry / Q000276:immunology; D011817:Rabbits; D055815:Young Adult
D000485:Allergens; D052179:Antigens, Plant; C102724:Art v 1 protein, mugwort; D016207:Cytokines; D007074:Immunoglobulin G; D010940:Plant Proteins; D007073:Immunoglobulin E