Expression of tryptase mRNA in AML cells.

Northern blot experiments were performed on leukemic blasts in 17 patients corresponding to lanes 1 (ALL, 2.7 ng/mL), 2 (M0, 3.9 ng/mL), 3 (M4eo, 395 ng/mL), 4 (M4eo, 881 ng/mL), 5 (M0, 120 ng/mL), 6 (M1, < 1 ng/mL), 7 (M3, 122 ng/mL), 8 (M4eo, 177 ng/mL), 9 (M1, 56 ng/mL), 10 (M2, 4.6 ng/mL), 11 (M4eo, 15.9 ng/mL), 12 (M2, 113 ng/mL), 13 (M6, 5.5 ng/mL), 14 (M4, 23.1 ng/mL), 15 (M3, 79.2 ng/mL), 16 (M4, 224 ng/mL), and 17 (M3 55.5 ng/mL). For detection of tryptase mRNA, an oligonucleotide probe specific for α-tryptase and a second probe specific for β-tryptase were applied. For control purposes, the membrane was hybridized with an oligonucleotide probe specific for β-actin. Using the α-tryptase probe, tryptase mRNA could be detected in all cases with elevated serum tryptase levels. By contrast, β-tryptase mRNA was detectable only in a small group of patients analyzed (ie, in AML M4eo). In the 2 AML cases with normal serum tryptase as well as in one case with ALL (normal serum tryptase level), no tryptase mRNA could be detected.