The use of lactate dehydrogenase for the detection of murine natural killer cell function, /

Abstract

Natural Killer (NK) cells are white blood cells that participate in the direct cellular elimination of tumor and virus-infected cells. NK cell function is determined through the use of cytotoxicity assays. Our study investigates the use of an LDH assay (Promega Cytotox 96® LDH assay) to characterize murine NK cells. Four target cell lines were tested for their effectiveness in this assay. Studies using 51Cr release assays have shown that MPC II and YAC-l cell lines are targeted for lysis by murine NK cells (positive controls) and that L1210 and P815 cell lines are not targeted for NK cell lysis (negative controls). The optimal number of target cells (total LDH two-fold higher than background) was 5,000 cells/lOOl-ll for P815 and YAC-l, 10,000 cells/lOOl-ll for L1210 and MPC II. The 4 and 24 spontaneous release values (percentage of the total LDH release) were as follows: P815: 0 and 46.651 %, YAC-l: 028.985%, L121O: 0 and 12.661 %, and MPC II: 13.490% and 41.542%. Experimental cytotoxicity assays were also performed, with the optimal number of target cells incubated with NK cells at various effector (NK) to target cell ratios. P815 experienced a low % cytotoxicity (0.369%) and was an effective negative control cell line. MPC II exhibited a high % cytotoxicity (25.8%) and was an effective positive control cell line. No specific LDH release was seen with YAC-l target cells at the effector to target cell ratios used in these studies. The LDH cytotoxicity assay is useful in determining murine NK cell cytotoxicty. The spontaneous and total release data along with the results of the LDH cytotxicity assays obtained from these positive and negative control target cell lines will aid in the determination of the functional activity of an NK cell preparation.