Analysis of the cross-reactivity between BtM and Der p 5, two group 5 recombinant allergens from Blomia tropicalis and Dermatophagoides pteronyssinus.
BACKGROUND
In tropical climates, sensitization to Bloma tropicalis and Dermatophagoides pteronyssinus is high and mainly directed to species-specific allergens. There is some cross-reactivity between extracts of these mites, probably due to the group 5 allergens that have high sequence homology.


OBJECTIVE
We used the radioallergosorbent test (RAST), RAST inhibition and immunoblotting inhibition experiments to investigate the cross-reactivity between the recombinant allergens BtM and Der p 5, expressed as glutathione S-transferase fusion proteins, to detect the epitopes involved and to analyze the importance of this cross-reactivity.


RESULTS
Seventy-nine percent of 48 patients sera were RAST positive to both recombinants, with a strong correlation (r = 0.8, p<0.0001). BtM inhibited 25 and 21.1% of IgE-binding to B. tropicalis and D. pteronyssinus extracts respectively and Der p 5 inhibited 22 and 24% of IgE-binding to D. pteronyssinus and B. tropicalis extracts. Furthermore, BtM inhibited 74.5% of IgE binding to Der p 5 and Der p 5 inhibited 72.4% of IgE-binding to BtM. RAST inhibition with BtM-derived synthetic peptides showed that peptide 4 (residues 35-50) and peptide 5 (residues 46-61) inhibited 37 and 16% of IgE-binding to BtM while peptides 5 and 2 (residues 14-30) were able to inhibit the IgE binding (32 and 28%, respectively) to Der p 5.


CONCLUSIONS
There is cross-reactivity between BtM and Der p 5, which explains almost all the cross-reactivity between the two mite extracts. This cross-reactivity seems to be related to epitope(s) at the C-terminal segment of these allergens.
Caraballo
L
L
Instituto de Investigaciones Inmunológicas, Universidad de Cartagena, Colombia.
Mercado
D
D
Jiménez
S
S
Moreno
L
L
Puerta
L
L
Chua
K Y
KY
D000485:Allergens / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D001667:Binding, Competitive / Q000276:immunology; D003429:Cross Reactions; D005982:Glutathione Transferase / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000378:metabolism; D008925:Mites / Q000276:immunology; D011852:Radioallergosorbent Test; D011993:Recombinant Fusion Proteins / Q000276:immunology
D000485:Allergens; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D006023:Glycoproteins; D011993:Recombinant Fusion Proteins; C101834:allergen Bt-M; D007073:Immunoglobulin E; D005982:Glutathione Transferase