Isoforms of the major allergen of birch pollen induce different immune responses after genetic immunization.
BACKGROUND
Recent publications indicate that immunization with plasmid DNA encoding allergens might represent a potential approach in allergen-specific immunotherapy.


OBJECTIVE
In the present study we have compared the immune responses induced by plasmid DNA encoding for two isoforms of Bet v 1, the major allergen of birch pollen.


METHODS
BALB/c mice were injected intradermally with plasmid DNA encoding for the genes of Bet v 1a (pCMV-Beta) and Bet v 1d (pCMV-Betd). In addition, the effect of immunostimulatory DNA sequences was investigated by appending and/or coinjecting CpG motifs. Antibody responses and IFN-gamma and IL-4 levels were measured by ELISA. Allergen-specific proliferation was determined by incorporation of [(3)H]-thymidine.


RESULTS
The two isoforms induced a similar humoral response. The lack of any IgE production and the ratio of IgG1 to IgG2a clearly indicated a Th-1-type response. The antisera against both isoforms were highly cross-reactive, which was supported by the energy plot indicating similar folding of the two protein isoforms. However, determination of IFN-gamma and IL-4 in the serum elicited a strikingly different cytokine profile during the course of the immune response. In contrast to pCMV-Beta, pCMV-Betd caused no significant allergen-specific proliferation and induced only marginal levels of the key cytokines.


CONCLUSIONS
Based on the assumption that the induction of a strong Th-1 type response is a prerequisite for successful treatment of allergy, our results favor the use of isoform Bet v 1a in combination with CpG motifs for a novel type of allergen immunotherapy based on plasmid DNA immunization. Additionally, the data also confirm the assumption that the antigen itself can have a marked influence on the immune response after genetic immunization.
Hartl
A
A
Institute of Chemistry and Biochemistry, University of Salzburg, Austria.
Kiesslich
J
J
Weiss
R
R
Bernhaupt
A
A
Mostböck
S
S
Scheiblhofer
S
S
Flöckner
H
H
Sippl
M
M
Ebner
C
C
Ferreira
F
F
Thalhamer
J
J
D000485:Allergens / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D000917:Antibody Formation; D052179:Antigens, Plant; D001483:Base Sequence; D016207:Cytokines / Q000096:biosynthesis; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D005260:Female; D017343:Genes, Plant; D006801:Humans; D007114:Immunization; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology; D010957:Plasmids / Q000235:genetics; D011058:Pollen / Q000235:genetics* / Q000276:immunology*; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014197:Trees / Q000235:genetics / Q000276:immunology
D000485:Allergens; D052179:Antigens, Plant; D016207:Cytokines; D017931:DNA Primers; D018744:DNA, Plant; D010940:Plant Proteins; D020033:Protein Isoforms; C061312:Bet v 1 allergen, Betula