IL15 and plasma cell myeloma: This hypothesis, that IL-15 broadens the functional response of immature NK cells, is further supported by evidence that degranulation and IFN-γ and TNF-α production from CD56bright NK cells are potently enhanced by exposure to multiple myeloma or acute myeloid leukemia target cells after in vivo therapy with the IL-15R agonist ALT803 (37).