Conjugation of immunostimulatory DNA to the short ragweed allergen amb a 1 enhances its immunogenicity and reduces its allergenicity.
BACKGROUND
Allergen immunotherapy is inconvenient and associated with the risk of anaphylaxis. Efforts to improve the safety of immunotherapy by means of chemical modification of allergens have not been successful because it greatly reduced their antigenicity. Recently, immunostimulatory DNA sequences (ISS or CpG motifs) have been shown to act as strong T(H)1 response-inducing adjuvants.


OBJECTIVE
We sought to determine whether conjugation of ISS to the major short ragweed allergen Amb a 1 results in enhanced immunotherapeutic potential in mice and decreased allergenicity in human subjects.


METHODS
A 22-mer ISS oligodeoxynucleotide (ISS-ODN) was coupled to Amb a 1 and used for immunization of mice, rabbits, and monkeys.


RESULTS
In mice the Amb a 1-ISS conjugate induced a T(H)1 response (IFN-gamma secretion), whereas Amb a 1 induced a T(H)2 response (IL-5 secretion). The T(H)1 response was not observed with an Amb a 1-non-ISS conjugate. Coinjection of Amb a 1 with ISS-ODN was much less effective in inducing a T(H)1 response. In mice primed for a T(H)2 response, injection with Amb a 1-ISS conjugate induced a de novo T(H)1 response and suppressed IgE antibody formation after challenge with Amb a 1. Amb a 1-ISS conjugate induced high-titer anti-Amb a 1 IgG antibodies in rabbits and cynomolgus monkeys, whereas Amb a 1 alone or Amb a 1 coinjected with ISS-ODN did not induce a detectable response. Amb a 1-ISS conjugate was less allergenic than Amb a 1 alone, as shown by a 30-fold lower histamine release from human basophils of patients with ragweed allergy, whereas mixing ISS-ODN with Amb a 1 did not reduce histamine release.


CONCLUSIONS
Amb a 1-ISS conjugate has an enhanced T(H)1-biased immunogenicity and reduced allergenicity. It may offer a more effective and safer approach for allergen immunotherapy than currently available methods.
Tighe
H
H
Department of Medicine and The Sam and Rose Stein Institute for Research on Aging, and the Department of Pediatrics, University of California San Diego School of Medicine, La Jolla, CA, USA.
Takabayashi
K
K
Schwartz
D
D
Van Nest
G
G
Tuck
S
S
Eiden
J J
JJ
Kagey-Sobotka
A
A
Creticos
P S
PS
Lichtenstein
L M
LM
Spiegelberg
H L
HL
Raz
E
E
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000818:Animals; D001491:Basophils / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006636:Histamine Release; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D015848:Interleukin-5 / Q000378:metabolism; D008252:Macaca fascicularis; D051379:Mice; D008807:Mice, Inbred BALB C; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D011817:Rabbits; D013154:Spleen / Q000378:metabolism; D013329:Structure-Activity Relationship; D018418:Th2 Cells / Q000276:immunology; D019444:Vaccines, DNA / Q000737:chemistry / Q000276:immunology*
D000485:Allergens; D007074:Immunoglobulin G; D015848:Interleukin-5; D019444:Vaccines, DNA; D007073:Immunoglobulin E