Analysis of the Cross–Reactivity between BtM and Der p 5, Two Group 5 Recombinant Allergens from Blomia tropicalis and Dermatophagoides pteronyssinus

Abstract

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 and Methods: 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. Conclusion: 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.

Nuclear Magnetic Resonance Structure and IgE Epitopes of Blo t 5, a Major Dust Mite Allergen

“…The locations of these four epitope residues agrees with the previous finding that BtM, the C-terminal 72 residues fragment of Blo t 5, has almost all the allergenic epitopes of the natural Blo t 5 in the B. tropicalis extract (39). Furthermore, radioallergosorbent test inhibition with BtM-derived synthetic peptides showed that a peptide from residues 75-90 can inhibit 37% of IgE binding to BtM (14), indicating that the major IgE binding epitope residues could be located in this C-terminal region of the protein. A more recent study also found that 75% of Blo t 5-sensitive patients were allergic to a fragment of Blo t 5 from residues 70 -117 of the protein (9).…”

“…Der p 5 and Blo t 5 share 43% identity in their amino acid sequences, and cross-reactivity analysis has shown that both these allergens only share a low degree of cross-reactivity and are species specific (11)(12)(13). However, it is also reported that 79% of 48 sera of atopic individuals were radioallergosorbent test positive to both recombinant Der p 5 and BtM, a C-terminal 72-residues fragment of Blo t 5 (14).…”

Der p 5 Crystal Structure Provides Insight into the Group 5 Dust Mite Allergens

“…The remaining 62 sera were from patients sensitized to either Der p 1 or Der p 2 or both. In data not shown, 22 of the 62 sera (35.5%) had IgE antibody binding to rDer p 5, in agreement with the range of reported prevalences of IgE antibody to this allergen (7,8,32,33), indicating that this construct is a good model of the natural allergen.…”

Responses of IgE, IgG1, and IgG4 to concanavalin A-binding Blomia tropicalis antigens in allergic patients

“…Most of the cross-reactivity between B. tropicalis and Dp extracts has been shown to be due to the low-molecular weight allergen components, in particular to the BtM/Blo t 5 and Der p 5 (14 kDa) or Blo t 3 and Der p 3 (25 kDa) allergens (20,21). In the present study, we demonstrated that there was an important IgE cross-reactivity with the Dp extract even when using the Bt-Con-A extract, suggesting that high-molecular weight allergens could also be involved in this cross-reactivity.…”