Ricerc@Sapienza

Natural Killer (NK) cells play a pivotal role in the immunosurveillance of Multiple Myeloma
(MM), but it is still undefined whether the NK cell functional properties underlying their protective
activity against MM are confined to distinct NK cell populations. Interestingly, herein we report that
the CD56lowCD16low NK cell subset displayed higher cytolytic activity compared to the other NK cell
subsets (i.e., CD56highCD16+/, CD56lowCD16high) against MM cells and its activity was impaired in
MM patients. Decreased DNAM-1 expression levels were observed on the CD56lowCD16low NK cells
during MM progression. Evaluating NK cell subset frequency after autologous hematopoietic stem
cell transplantation, we found that CD56lowCD16low NK cells recovered earlier after transplantation.
Overall, our data denote a key role of CD56lowCD16low subpopulation in the killing of MM cells
and suggest that the reconstitution of CD56lowCD16low subpopulation after HSCT could be a useful
approach of adoptive immunotherapy in the treatment of relapsed/refractory MM patients.