Spontaneous production and release of tryptase in cultured AML cells.

AML cultures were performed using isolated bm MNCs. The figure shows a representative culture experiment performed in a tryptase⁺AML patient (secondary AML, serum tryptase level, 30.4 ng/mL). Cells were cultured in RPMI 1640 medium supplemented with 10% FCS (37°C; 5% CO₂) for 30 days. Tryptase levels (y axis) in cell-lysates (●) and supernatants (■) were measured serially by FIA. As visible, significant levels of tryptase were detected in these cultures. Cellular tryptase levels (pg/cell) as well as the tryptase levels in the supernatants increased during a first phase of culture. Thereafter, cellular levels of tryptase decreased, whereas, in the supernatants, tryptase remained at a high level.