Am. J. Respir. Crit. Care Med., Vol 155, No. 1, Jan 1997, 343-350.
Sensitization to Blomia tropicalis in patients with asthma and identification of allergen Blo t 5
LK Arruda, LD Vailes, TA Platts-Mills, E Fernandez-Caldas, F Montealegre, KL Lin, KY Chua, MC Rizzo, CK Naspitz and MD Chapman
Asthma and Allergic Diseases Center, Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
In tropical and subtropical regions of the world, allergens produced by
Blomia tropicalis are an important cause of IgE-mediated sensitization
among patients with asthma. We compared the relative importance of
sensitization to the two mite species among asthma patients from Florida,
Puerto Rico, and Brazil (n = 83), who were concurrently exposed to B.
tropicalis and D. pteronyssinus, with patients from the United States and
from the United Kingdom (n = 56) exposed to D. pteronyssinus. In addition,
molecular cloning techniques were used to clone and express a major B.
tropicalis allergen. There were significant differences between IgE
antibody responses to B. tropicalis and D. pteronyssinus that were related
to exposure: only 22% of patients exposed to both species had a high ratio
(> 10) of IgE D. pteronyssinus:B. tropicalis, whereas 68% of patients
exposed only to D. pteronyssinus had a ratio of > 10 (p < 0.001). A
major 14-kD allergen (Blo t 5), cloned from a B. tropicalis cDNA library,
showed 43% sequence homology to D. pteronyssinus Der p 5. Recombinant Blo t
5 produced in E. coli reacted with 45 to 69% of sera from B. tropicalis-
allergic asthmatics and induced positive immediate skin tests at 10(-3) to
1 microg/ml. In vivo and in vitro comparisons of IgE responses to B.
tropicalis, D. pteronyssinus, rBlo t 5, and rDer p 5, showed that B.
tropicalis has unique allergens that cause specific IgE responses. The
results suggest that B. tropicalis is an independent cause of sensitization
and that use of recombinant Blo t 5 should lead to a better understanding
of the role of B. tropicalis in causing asthma in tropical environments.
