Terahertz (THz) radiation sources are now being used in a host of military, defense, and medical applications.
Widespread employment of these applications has prompted concerns regarding the health effects associated with THz
radiation. In this study, we examined the gene expression profile of mammalian cells exposed to THz radiation. We
hypothesized that if THz radiation couples directly to cellular constituents, then exposed cells may express a specific
gene expression profile indicative of ensuing damage. To test this hypothesis, Jurkat cells were irradiated with a
molecular gas THz laser (2.52 THz, 636 mWcm-2, durations: 5, 10, 20, 30, 40, or 50 minutes). Viability was assessed 24
h post-exposure using MTT assays, and gene expression profiles were evaluated 4 h post-exposure using mRNA
microarrays. Comparable analyses were also performed for hyperthermic positive controls (44°C for 40 minutes). We
found that cellular temperatures increased by ~6 °C during THz exposures. We also found that cell death increased with
exposure duration, and the median lethal dose (LD50) was calculated to be ~44 minutes. The microarray data showed that
THz radiation induced the transcriptional activation of genes associated with cellular proliferation, differentiation,
transcriptional activation, chaperone protein stabilization, and apoptosis. For most genes, we found that the magnitude of
differential expression was comparable for both the THz and thermal exposure groups; however, several genes were
specifically activated by the THz exposure. These results suggest that THz radiation may elicit effects that are not
exclusively due to the temperature rise created during THz exposures (i.e. thermal effects). In future work, we plan to
verify the results of our microarray experiments using qPCR techniques.