Detection of α- and β-tryptase mRNA by RT-PCR.

(A) RT-PCR was performed with bm RNA from 9 patients with AML. The respective lanes are 1 (M1, 20.5 ng/mL), 2 (M2, 41.6 ng/mL), 3 (M2, 26.9 ng/mL), 4 (M1, 4.1 ng/mL), 5 (M3, 55.5 ng/mL), 6 (M3, 6.2 ng/mL), 7 (M4eo, 77 ng/mL), 8 (M4eo, 15.7 ng/mL), and 9 (M4eo, 881 ng/mL). In all cases with elevated serum tryptase (lanes 1,2,3,5,7,8,9) and in one patient with normal serum tryptase (lane 4), tryptase cDNA of 383 bp was obtained by RT-PCR. Restriction enzyme digestion (Dra III) revealed the presence of β-tryptase cDNA in 5 of 9 patients with AML (restriction fragments of 263 bp and 120 bp). The human mast cell line HMC-1 (lane 10) but not human fibroblasts (lane 11) was also found to express α- and β-tryptase mRNA. β-Actin cDNA was obtained from all samples (B). RT-PCR products for α- and β-tryptase obtained from plasmids containing α- and β-tryptase cDNA were subjected to electrophoresis before (α, β) and after (α⁺, β⁺) digestion with Dra III (C).