Immunoglobulin E reactivity of native Blo t 5, a major allergen of Blomia tropicalis.
BACKGROUND
Blo t 5 is a major allergen of Blomia tropicalis and its complementary DNA (cDNA) has been expressed in both prokaryotic and eukaryotic expression systems. Although the recombinant Blo t 5 has been well characterized, relatively less is known about its native counterparts and the allergenicity comparison of the native and recombinant Blo t 5 allergens has not been reported.


OBJECTIVE
The aims of this study are to characterize the native counterpart of Blo t 5, and compare the allergenicity of native and recombinant Blo t 5 by in vivo and in vitro assays.


METHODS
Native Blo t 5 were purified by immuno-affinity chromatography and characterized by proteomic means. The allergenicity of the allergen was evaluated by skin prick tests, human IgE ELISA, ELISA inhibition and histamine release assays.


RESULTS
Native Blo t 5 consists of at least five distinct isoforms, ranging from pI 3 to 5.5. Allergenicity assessment of recombinant and native Blo t 5 based on skin reaction, IgE-binding capacity and histamine release in allergic individuals indicated that there was a good correlation between both forms of Blo t 5 in general. However, data from IgE ELISA inhibition assay revealed the presence of additional unique IgE epitopes in native Blo t 5.


CONCLUSIONS
At least five distinct isoforms of Blo t 5 have been identified. Comparative assessment of native and recombinant Blo t 5 revealed that the allergenicity of these two forms was similar but not completely identical suggesting that the various isoforms of native Blo t 5 may exhibit additional unique IgE epitopes.
Yi
F C
FC
Department of Paediatrics, National University of Singapore, Singapore, Singapore.
Chua
K Y
KY
Cheong
N
N
Shek
L P
LP
Lee
B W
BW
D000293:Adolescent; D000485:Allergens / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D052179:Antigens, Plant; D015153:Blotting, Western / Q000379:methods; D002648:Child; D002675:Child, Preschool; D004306:Dose-Response Relationship, Immunologic; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D006636:Histamine Release / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000096:biosynthesis*; D008925:Mites / Q000276:immunology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000276:immunology; D012882:Skin Tests
D000485:Allergens; D052179:Antigens, Plant; D000939:Epitopes; D011994:Recombinant Proteins; C094701:allergen Blo t 5; D007073:Immunoglobulin E