Introduction: Cytotoxic CD8+ cells and natural killer (NK) cells kill virus-infected or transformed cells by apoptosis. A family of serine proteases called granzymes is potent pro-apoptotic granules and granzymes can induce target cell death. We investigated the amount of secreted granzymes after stimulation of phytohemagglutinin (PHA) and NK cells in whole blood.
Method: Ten patients with rheumatologic diseases and 15 patients with gastric cancers were enrolled. PHA (Cellestis, Australia) and PROMOCATM (ATGen, Korea), a recombinant cytokine that specifically activates NK cells were used to stimulate cytotoxic lymphocytes. Granzymes in the supernatants after 24 hours stimulation of whole blood were measured by MILLIPLEXrMAP (EMD Millipore, USA).
Results: Granzyme A was not secreted after stimulation of PHA and PROMOCATM, repectively. The level of granzyme B secreted after stimulation of PROMOCATM was significantly different in patients with rheumatologic diseases [median 5.2 pg/mL (range 0.06-32.8)], patients with early gastric cancers [median 263.9 pg/mL (range 68.3-1019.5)], and patients with advanced gastric cancers [median 112.2 pg/mL (range 2.5-142.2], respectively (p=0.00016 by Kruskal-Wallis test). The amount of granzyme B secreted after PHA stimulation was higher than that of granzyme B secreted after PROMOCATM stimulation. There was a significant difference between patients with rheumatologic diseases and patients with all gastric cancers for secreted granzyme B after PHA stimulation (p=0.00028).
Conclusion: The significantly differed granzyme B secreted after stimulation of PHA and PROMOCATM in whole blood were observed in patients with rheumatologic diseases and gastric cancers. It is needed to evaluate the usefulness of this study for more patients.