Immunological Effects of Cold Atmospheric Plasma-Treated Cells in Comparison with Those of Cells Treated with Lactaptin-Based Anticancer Drugs

The ability of dying cancer cells to induce an anticancer immune response can increase the effectiveness of anticancer therapies, and such type of death is termed immunogenic cell death (ICD). Cells can die along the ICD pathway when exposed not only to chemo- and immunotherapeutics, but also to various types of radiation, such as ionizing radiation and cold atmospheric plasma jets (CAP). We have previously shown that CAP, lactaptin, and a recombinant vaccinia virus encoding lactaptin induce in vitro molecular changes typical of ICD in cancer cells. In the current work, we treated MX-7 rhabdomyosarcoma cells with CAP and lactaptin-based anticancer drugs and evaluated the immunological effects of the treated cells. We showed that dendritic cells (DCs) captured cells treated with various ICD inducers with different efficiency. CAP-treated cells were weakly potent in inducing the maturation of DCs according to MHC II externalization. Moreover, CAP-treated cells were worse in the stimulation of IFN-α release in vitro and were poorly captured by spleen DCs in vivo. Under the irradiation conditions used, CAP was not capable of activating a significant immunological anti-tumor effect in vivo. It is possible that modifications of the CAP irradiation regimen will enhance the activation of the immune system.