The immune cells with CD16 and CD56 on their surface, which are impoant in immunological surveillance and natural defense against virus infected and malignant cells are-

NATURAL KILLER (NK) CELLS. These lymphocytes do not have B or T cell markers, nor are these cells dependent upon thymus for development unlike CD4+ and CD8+ T cells. NK cells carry surface molecules of CD2, CD16, and CD56, but negative for T cell marker CD3. NK cells are morphologically distinct from B and T cells in being large granular lymphocytes. NK cells are pa of the natural or innate immunity. These cells recognize antibody-coated target cells and bring about the killing of the target directly; this process is termed as antibody- dependent cell-mediated cytotoxicity (ADCC). This mechanism is paicularly operative against viruses and tumour cells. Ref: TEXTBOOK OF PATHOLOGY 6th EDITION - HARSH MOHAN PAGE NO:64