Tryptase

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

Tryptase, a serine protease, is rich in the secretory granules of mast cells and basophils. It is a sensitive and specific immunohistochemical marker for mast cells (though it will also react with basophils but to a lesser degree). Tryptase is useful, along with CD117, in the diagnosis of mast cell disease (e.g. mastocytosis) among others.