An extensive study of human IgE cross-reactivity of Blo t 5 and Der p 5.
BACKGROUND
Dual sensitization by Blomia tropicalis and Dermatophagoides pteronyssinus mites is common in tropical and subtropical countries. The human IgE cross-reactivity between clinical important group 5 allergens, Blo t 5 and Der p 5, remains controversial.


OBJECTIVE
This study was undertaken to assess the levels of the IgE cross-reactivity between Blo t 5 and Der p 5 by using sera from a large cohort of asthmatic children in subtropical and tropical countries.


METHODS
Purified recombinant Blo t 5 and Der p 5 were produced in Pichia pastoris and tested against sera from 195 asthmatic children. The IgE cross-reactivity was examined by direct, inhibitory and competitive human IgE enzyme-linked immunosorbent assay as well as skin prick tests.


RESULTS
The Blo t 5 IgE responses were 91.8% (134 of 146) and 73.5% (36 of 49) for Taiwanese and Malaysian sera, respectively. The Blo t 5 specific IgE titers were significantly higher than those of Der p 5 (P <.02). The correlation of IgE reactivity between Blo t 5 and Der p 5 was low, and only limited cross-reactivity was observed. This was further confirmed by the dose-response inhibition studies. Skin prick tests performed on asthmatic children in Thailand also showed differential IgE response to Blo t 5 and Der p 5.


CONCLUSIONS
By using a large panel of asthmatic sera and a combination of in vitro and in vivo assays, the major allergen of B tropicalis in tropical and subtropical regions, Blo t 5, exhibits low levels of IgE cross-reactivity with homologous Der p 5. These findings suggest that highly specific clinical reagents are necessary for precise diagnosis and immunotherapeutic treatment of sensitization to group 5 mite allergens.
Kuo
I Chun
IC
Department of Paediatrics, Faculty of Medicine, National University of Singapore.
Cheong
Nge
N
Trakultivakorn
Muthita
M
Lee
Bee Wah
BW
Chua
Kaw Yan
KY
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000096:biosynthesis / Q000276:immunology*; D039741:Antigens, Dermatophagoides / Q000096:biosynthesis / Q000276:immunology*; D052179:Antigens, Plant; D060829:Arthropod Proteins; D001249:Asthma / Q000276:immunology*; D002648:Child; D015331:Cohort Studies; D003429:Cross Reactions; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood*; D010843:Pichia / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D012882:Skin Tests
D000485:Allergens; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D060829:Arthropod Proteins; C451239:Dermatophagoides pteronyssinus antigen p 5; D011994:Recombinant Proteins; C094701:allergen Blo t 5; D007073:Immunoglobulin E