<prompt> Not true regarding NK cells is?Active against malignant cellsInvolve MHC antigen for killing micro-organismsFirst line defense against viral infectionsNo prior sensitization required  <response>: Ans. b Involve MHC antigen for killing microorganisms Ref: Robbins 9thpg 192; 8thpg 188Natural Killer Cells Destroy virus-infected cells and tumor cells without prior exposure;NK cells do not require MHC for killing micro-organismsSurface molecules of NK cells are CD16 CD56 