Tryptase immunoelectron microscopy.

(A) Blood basophil from a patient with chronic phase CML. Tryptase-immunoreactive material is localized to a subset of granules (arrows; original magnification × 5000; inset, × 10 000). (B) Basophil of a healthy donor shows no tryptase expression by immunoelectron microscopy (original magnification × 6500; inset × 13 000). (C) Tryptase immunoelectron microscopy of a CB culture–derived basophil (IL-3, day 13); no significant amounts of tryptase could be detected (original magnification × 4000). (D) Tryptase immunoelectron microscopy of a CB culture–derived MC (SCF, day 28). In this cell tryptase-reactive material could be detected. Note surface projections and granular staining pattern (original magnification × 12 500). 1 bar = 1 μm.