Transcriptional regulation is a very important and pivotal function in myriad biological responses. Thus, methods to determine transcriptional activity are required in not only basic medical research but also in drug discovery. We established a novel reporter construct using human secreted embryonic alkaline phosphatase (SEAP) and Epstein-Barr virus nuclear antigen (EBNA) 1, which can maintain constructs synchronized to host cell replication. We established nuclear factor-kappa B (NFkB) driven SEAP expression construct and then, introduced it into culture cells. The cells maintain the reporter construct for a long period in the culture and produce SEAP into culture supernatant in response to a specific ligand, lipopolysaccharide. Measuring SEAP with chemiluminescence makes it possible to get high standard dynamic range applying to high-throughput screening in drug discovery. 
Next, we have examined the possibility whether or not human gamma delta T cells can be applied for the novel immunotherapies. Because IL-18 is a kind of cytokines that enhances cytotoxicity and activity of human gamma delta T cells through NFkB activation, we have focused on the activity and signaling of IL-18. In this study, we modified the previous reporter cell that can determine the transcription activity of NFkB to express two subunits consisted of human IL-18 receptor. The modified cells secreted SEAP in response to treatment with human recombinant IL-18 in a concentration-dependent manner. 
 Finally, in order to identify drugs mimicking IL-18 biological activity or possessing inhibitory effects on IL-18-induced NFkB, we demonstrated drug screening using number of extracts derived from marine bacteria and synthetic compounds.