Dictionary of Allergies .. Blomia tropicalis

In tropical and subtropical climates the mite Blomia tropicalis is commonly found in homes. Many patients with allergic disease in these areas have positive skin prick tests to B. tropicalis (up to 90%), and sensitization to this mite is associated with asthma. However D. pteronyssinus usually coexists in homes with high levels of B. tropicalis and is often numerically dominant. As a result asthmatics exposed to B. tropicalis tend also to be exposed to D. pteronyssinus and may have raised serum-specific IgE to both mite species. 

A major 14 kDa B. tropicalis allergen, Blo t 5, has been identified, cloned and sequenced [1]. Blo t 5 shows 40% sequence identity with D. pteronyssinus allergen Der p 5, and approximately 70% of atopic patients exposed to B. tropicalis make IgE antibody to this allergen. Both recombinant allergens have been shown to give positive skin test responses in patients sensitized to the respective mite species[2]. In conclusion, this study provides in vivo evidence of the presence of allergens in B. tropicalis which cross-react with IgE antibodies to allergens of D. pteronyssinus, and that the IgE response to group 5 allergens is species specific. These results suggest that, in areas where B. tropicalis forms part of the acarofauna, sensitization to this mite is an independent risk factor for asthma and should be included in the evaluation of immediate hypersensitivity in patients who are exposed in their homes [3].See Suidasia.

References

1. Arruda LK et al: Blomia tropicalis allergen Blo t5: Homology to D. Pteronyssinus Der p 5. Abstracts of XV International Congress and Annual Meeting of EAACI, Stockholm June 6 - July 1, 1994, Hogrefe and Huber p.34.

2. Arruda LK, Vailes LD, Platts-Mills TAE et al. Sensitization to Blomia tropicalis in patients with asthma and identification of allergen Blo t 5. Am J Respir Crit Care Med 1997;155: 343-350.

3. Simpson, A., Green, R., Custovic, A., Woodcock, A., Arruda, L. K. & Chapman, M. D. Skin test reactivity to natural and recombinant Blomia and Dermatophagoides spp. allergens among mite allergic patients in the UK. Allergy, 2003:58(1):53-56.