IL15 and nasopharyngeal carcinoma: In contrast, γδ-CTLs expanded from NPC patients exhibited poorer cytotoxicity against the same NPC cells [121] Furthermore, when supernatants of NK cell cultures were assessed for cytokine(s) production, those of cultured NK cell from NPC patients had the lowest production of IFNγ but higher production of IL-12, IL-15 and TNF-α.