Assessing Natural Killer Cell Cytotoxicity Against Multiple Myeloma Cells with IL-6 and sIL-6R

Multiple myeloma (MM) is a blood cancer affecting plasma cells. Proliferation of abnormal plasma cells in the bone marrow leads to reduced production of healthy antibodies that recognize infections. Malignant plasma cells in MM produce unusable antibodies that accumulate in the body. MM can result in complications including bone fragility, anemia, kidney failure, higher susceptibility to infection, etc. While MM remains to be an incurable form of cancer, research into cellular immunotherapy like the use of natural killer (NK) cells suggest the possibility for a treatment that can cure multiple myeloma. NK cells are lymphocytes of the innate immune system which can recognize and attack malignant cells without prior activation or recognition, making their functions highly attractive to study. Cytokines like interleukin-6 (IL-6) are inflammatory response messengers that are suspected to hinder cytotoxic activity for NK cells. Here we studied interactions between NK and MM cells through cultures of NK-92MI and MM.1s cells to assess the cytotoxicity of NK-92 MI cell with and without added IL-6 and soluble IL-6 receptor (sIL-6R). Our results suggest that the viability of MM.1s cells was significantly increased in the presence of IL-6 and sIL-6R, suggesting that IL-6 and sIL-6R play a critical role in the survival of MM cells from cytotoxic NK-92 MI cells. Our findings provide an interesting insight into therapeutic implications of NK cells in treating MM, particularly in the bone marrow tumor microenvironment enriched with IL-6 and sIl-6R.