Medical Diagnosis Exams

Natural Killer (NK) cells are a type of lymphocyte (a white blood cell) and a crucial component of the innate immune system. They play a major role in the host-rejection of both tumors and virally infected cells. NK cells are identified by their expression of surface markers CD16 and CD56 and lack of CD3, which distinguishes them from T cells.

CD16 (FcγRIII): This receptor is important for antibody-dependent cellular cytotoxicity (ADCC). CD16 binds to the Fc region of antibodies that coat a target cell, leading to the release of cytotoxic substances that kill the target cell.
CD56 (NCAM, Neural Cell Adhesion Molecule): This marker is used to identify NK cells within blood and immune tissue. NK cells can be further divided into two subsets based on the density of CD56 expression: CD56^dim (which are more cytotoxic) and CD56^bright (which are better at cytokine production).
Lack of CD3:
NK cells do not express CD3, a marker typically found on T cells. This absence is crucial for distinguishing NK cells from T-cell subsets during immunophenotyping.Natural Killer (NK) cells are a type of lymphocyte (a white blood cell) and a crucial component of the innate immune system. They play a major role in the host-rejection of both tumors and virally infected cells. NK cells are identified by their expression of surface markers CD16 and CD56 and lack of CD3, which distinguishes them from T cells.