Background and Aims We have previously reported that the exposure of human monocytic cells THP-1 to pulsed radiofrequency (PRF) electric field increased the mRNA for β-endorphin (J Pain Res 2018;11:2887–96), while it has not yet been clarified whether PRF application increases the production of acute inflammatory cytokines or chemokines from these cells. If the latter occurs, the beneficial roles of monocytic cells to alleviate pain through the production of β-endorphin may be enhanced because these cytokines/chemokines have a property to recruit and stimulate the donor for β-endorphin.

Methods PRF was applied for 15 min at the maximum power by using a NeuroTherm NT-500 radiofrequency generator to the pellet of THP-1 cells sedimented in a microtube filled with the culture medium incubated at 37°C as previously described. (J Pain Res 2018;11:2887–96) After the PRF application, cell culture continued for pre-selected period and the supernatant of THP-1 cells was collected for multiplex immunoassay (Bio-Rad Bio-Plex #m500kcaf0y).

Results Level of RANTES, chemokine c-c motif ligand 5 (CCL5), as well as those of two acute inflammatory cytokines, IL-1β and IL-15, in the supernatant of THP-1 cells was significantly increased by PRF application as compared by those without application of PRF.Because RANTES plays an active role in recruiting leukocytes, and the latter cytokines stimulate the recruited leukocytes, the increase in the production of these cytokines/chemokines may enhance the beneficial action of PRF to alleviate pain.

Conclusions Exposure of THP-1 cells to the electric field of PRF for 15 min increased the production of RANTES, IL-1β and IL-15 from these cells.