Table 2. Variations in phenotypic and functional NK-cell parameters as detected in the circulation of multiple myeloma patients.

Ref.	NK cell number	Activation status	Activating receptors	Cytotoxicity	Notes
44	Increased			Unchanged	Increased NK also in MGUS
45	Unchanged	Unchanged
46	Increased			Decreased	Increased NK also in MGUS
47	Increased in BM				Increased NK also in MGUS
48			Decreased CD16 Decreased CD244 Unchanged KLRK1 Unchanged NCR		Trend toward reduced KLRK1 levels in MM
49			Decreased KLRK1		Bortezomib increased MICA levels on MM cells
50				Decreased	Stage-dependent decrease
51			Decreased KLRK1		Not linked with soluble MICA levels
52	Increased also in BM

Abbreviations: BM, bone marrow; KLRK1, killer cell lectin-like receptor subfamily K, member 1; MICA, HC class I polypeptide-related sequence A; MGUS, monoclonal gammopathy of undetermined significance; MM; multiple myeloma; NCR, natural cytotoxicity triggering receptor; NK, natural killer.