Granzyme B is a useful biomarker for cytotoxic T-lymphocytes and natural killer cells, and may aid in differentiating between tumors arising from these cell types and tumors arising from other hematolymphoid cell types.
Granzyme B is a serine protease that is the main component in granule-mediated targeted cell lysis. Cytotoxic T-lymphocytes (CTL) and Natural-Killer (NK) cells store granzyme B-containing granules in their cytoplasm and release them during CTL-mediated targeted cell lysis (the ‘cell-mediated’ component of the immune response). After release from the CTL, granzyme B binds its receptor on the target cell, is endocytosed, and remains in the endocytic vesicle until released by perforin. Once released into the target cell cytoplasm, granzyme B can affect cell death via two pathways: 1) initiating a caspase cascade that leads to rapid DNA fragmentation of the target cell (apoptosis) or 2) mediating the release of cytochrome c from the mitochondria, which leads to cell death via necrosis.
Disease State: Anaplastic Large Cell Lymphoma (Systemic or Cutaneous), NK/T Cell Lymphoma, Nasal Type, Peripheral T Cell Lymphoma, NOS (of Large Cell Type), T Cell Non-Hodgkin Lymphoma (not otherwise classified)
CPT Code(s): 88342 or 88341 (reference only; CPTs may vary)
Turnaround Time: Within 1-2 business days of receipt
Schedule: Monday - Friday
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR -
• 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm