γδT cell receptor (TCR)-positive T cells, which control the innate immune system, display anti-tumor immunity as well as other non-immune-mediated anti-cancer effects. γδT cells expanded ex vivo by nitrogen-containing bisphosphonate (N-BP) treatment can kill tumor cells. N-BP inhibits farnesyl pyrophosphate synthase in the mevalonate pathway, resulting in the accumulation of isopentenyl pyrophosphate (IPP), which is a stimulatory antigen for γδT cells. We have previously observed that as they get closer, migrating γδT cells increase in speed toward target multiple myeloma (MM) cells. In the present study, we investigated the γδT cell chemotactic factors involving using a micro total analysis system-based microfluidic cellular analysis device. The addition of supernatant from RPMI8226 MM cells treated with the N-BP zoledronic acid (ZOL) or the addition of IPP to the device induced chemotaxis of γδT cells and increased the speed of migration compared to controls. Analysis of the ZOL-treated RPMI8226 cell supernatant revealed that it contained IPP secreted in a ZOL-dose-dependent manner. These observations indicate that IPP activates the chemotaxis of γδT cells toward target MM cells treated with ZOL.
Keywords: Chemotaxis; Isopentenyl pyrophosphate; Multiple myeloma; Tumor immunity; γδT cells.
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