Characterization of the human natural killer (NK) cell in blood and lymphoid organs

The human natural killer (NK) cell in peripheral blood is a non-thymus-dependent, (Fc+ C3-), Ig-bearing lymphocyte and is probably identical to the human K cell, although not requiring the Fc receptor, in contrast to the K cell, for the lytic process. The human NK cell in tonsil and lymph node, on the other hand, is a non-Ig- bearing T lymphocyte, lacking both Fc and C3 receptors.