Monocytic Suppressor Cells Derived From Peripheral Blood Suppress Xenogenic Natural Killer Cell Lysis

Background

Myeloid-derived suppressor cells (MDSCs) were initially found to contribute to immunosuppression in tumor patients and have recently been recognized as a subset of innate immune cells that are capable of regulating adaptive immunity. A variety of innate immune stimuli, such as lipopolysaccharide, act as a double-edged sword, inducing both the maturation of dendritic cells and the expansion of MDSCs.

Methods

We isolated MDSCs from peripheral blood mononuclear cells (PBMCs) and examined the suppressive effect of MDSCs against xenocytotoxicity mediated by YT cells, a natural killer–like cell line, with the use of the lactate dehydrogenase assay method.

Results

Although primed MDSCs induced no significant suppression in YT cell–mediated cytotoxicity, activated MDSCs significantly suppressed the xenogenic cytotoxicity.

Conclusions

These findings indicate that MDSCs have a great deal of potential as a therapeutic strategy for dealing with xenograft rejection. Further investigations of the underlying mechanisms will facilitate the development of this therapeutic strategy.