Sensitization to Blomia tropicalis in patients with asthma and identification of allergen Blo t 5.
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.
Arruda
L K
LK
Asthma and Allergic Diseases Center, Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Vailes
L D
LD
Platts-Mills
T A
TA
Fernandez-Caldas
E
E
Montealegre
F
F
Lin
K L
KL
Chua
K Y
KY
Rizzo
M C
MC
Naspitz
C K
CK
Chapman
M D
MD
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D001249:Asthma / Q000276:immunology*; D001483:Base Sequence; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D003001:Cloning, Molecular; D005431:Florida; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D008925:Mites / Q000276:immunology*; D008969:Molecular Sequence Data; D011647:Puerto Rico; D011994:Recombinant Proteins / Q000276:immunology; D017385:Sequence Homology; D012882:Skin Tests; D014329:Tropical Climate
D000485:Allergens; D039741:Antigens, Dermatophagoides; D052179:Antigens, Plant; D006023:Glycoproteins; D011994:Recombinant Proteins; C094701:allergen Blo t 5; D007073:Immunoglobulin E