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Medline ® Abstract for Reference 9

of 'Laboratory tests to support the clinical diagnosis of anaphylaxis'

Expression of alpha-tryptase and beta-tryptase by human basophils.
Jogie-Brahim S, Min HK, Fukuoka Y, Xia HZ, Schwartz LB
J Allergy Clin Immunol. 2004;113(6):1086.
BACKGROUND: Alpha and beta-tryptase levels in serum are clinical tools for the evaluation of systemic anaphylaxis and systemic mastocytosis. Basophils and mast cells are known to produce these proteins.
OBJECTIVE: The current study examines the effect of the alpha,beta-tryptase genotype on basophil tryptase levels and the type of tryptase stored in these cells.
METHODS: Tryptase extracted from purified peripheral blood basophils from 20 subjects was examined by using ELISAs measuring mature and total tryptase and by using an enzymatic assay with tosyl-Gly-Pro-Lys-p-nitroanilide. Tryptase genotypes (4:0, 3:1, and 2:2 beta/alpha ratios) were assessed by using a hot-stop PCR technique with alpha,beta-tryptase-specific primers. Total alpha,beta-tryptase mRNA was measured by means of competitive RT-PCR, and ratios of alpha to beta-tryptase mRNA were measured by means of hot-stop RT-PCR.
RESULTS: Tryptase in all but one of the basophil preparationswas mature and enzymatically active. Tryptase quantities in basophils were less than 1% of those in tissue mast cells. Tryptase genotypes (beta/alpha) among the 20 donors were 4:0 in 7, 3:1 in 7, and 2:2 in 6. Tryptase protein and mRNA levels per basophil were not affected by the tryptase genotype.
CONCLUSION: Basophils from healthy subjects contain modest amounts of mature and enzymatically active tryptase unaffected by the tryptase genotype.
Division of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Virginia Commonwealth University, PO Box 980263, Richmond, VA 23298, USA.