K cells
Last reviewed 01/2018
- cells of the inate immune system
- are mononuclear and have lymphocyte morphology
- their different surface characteristics however prevent them from being classified as either B or T cells.
- also known as “large granular lymphocytes” (LGLs)
- mainly found in the circulation
- comprise between 5-11% of the total lymphocyte fraction
- possess receptors for immunoglobulin type G (IgG)
- also contain two unique cell surface receptors
known as killer activation receptor and killer inhibition receptor
- activation of killer activation receptor initiates cytokine (“communication”) molecules from the cell
- activation of the killer inhibition receptor inhibits the cytokines
- have an important role in attacking virally-infected cells in addition to certain tumour cells
- destruction of infected cells is achieved through the release of perforins and granyzymes from its granules, which induce apoptosis (programmed cell death)
- able to secrete interferon-alpha
- interferon alpha prevents healthy host cells from becoming infected by a virus; and augments the T cell response to other virally infected cells
- cells lyse antibody-coated cells in the absence of complement by attaching to the Fc potion of the antibody molecule