| Summary: | 碩士 === 長庚大學 === 復健科學研究所 === 94 === Background and Purpose: Nasopharyngeal carcinoma (NPC) is a common cancer in South China. Natural killer (NK) cells can induce the death of carcinoma cell by employing the perforin/granzyme-mediated cytotoxicity (necrosis and apoptosis), whereas platelets attenuate the ability of NK cells to destroy carcinoma cells. Exercise is associated with intensity-dependent immune response and platelet reactivity. This study was designed to investigate how short-term exercise affects platelet-impeded cytotoxicity of NK cell to NPC cells and its underlying mechanisms. Methods and Results: Thirty healthy sedentary men performed on three occasions, moderate exercise (ME, 60%VO2Max for 40 min), severe exercise (SE, up to VO2Max) and SE preceded by ME (MSE). Blood samples were collected before and immediately after exercise. Leukocyte and platelet counts, intracellular perforin and granzyme B contents in NK cells, cytotoxicity of NK cell to NPC cells, caspase-3, -8 and -9 activation as well as PS exposure (phosphatidylserine exposure) and DNA fragmentation of NPC cells were determined. The results demonstrated that (1) SE increased NK cell and platelet concentration in blood, and was accompanied by an elevation in perforin and granzym B levels of NK cells; although cytotoxicity of NK cell to NPC cells was enhanced by SE, co-incubating NK cells with platelets attenuated the ability of tumor PSexposure and DNA fragmentation following this exercise. (2) ME did not increase NK cell number and perforin and granzyme B contents, NK-NPC interaction as well as PS exposure and DNA fragmentation of NPC cells. (3) MSE increased NK cell, perforin and granzyme B. Moreover, with platelet, NK cell-NPC cell interaction enhanced contrarily and NPC cell apoptosis increased. Conclusions: SE increases the number of NK cell, and their perforin and granzyme B contents, NPC cell apoptosis, but simultaneously increases platelet counts and augments the extent of platelet-impeded cytotoxicity of NK cells to NPC cells. Conversely, ME influences neither NK-NPC interaction nor the functional behavior of NK/platelet with regard to NPC cells. MSE increases NK cell function and suppressed platelet-impeded cytotoxicity of NK cells to NPC cells. Therefore, NPC cell apoptosis increases. Clinical Relevance: The findings provide new insight into the benefit and the risk of exercise modulating survival and death of the tumor in patients with NPC.
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