Killercell

Killercell is a term used in immunology to refer to cytotoxic immune effector cells that destroy target cells, most commonly natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). These cells are central to the body's defense against virus-infected cells and malignant transformations, and they can kill targets without prior exposure in the case of NK cells or after antigen-specific activation in CTLs.

Natural killer cells originate from lymphoid progenitors and mature in the bone marrow and secondary lymphoid tissues. They patrol the blood and tissues, identifying stressed cells through a balance of activating and inhibitory receptors. NK cells induce target cell death primarily through the release of cytotoxic granules containing perforin and granzymes, and can also trigger death receptor pathways via FasL or TRAIL. NK cells are capable of antibody-dependent cellular cytotoxicity (ADCC) through the CD16 receptor, enabling them to recognize antibody-coated targets.

Cytotoxic T lymphocytes develop from naive T cells that have been activated by specific antigens presented on MHC class I molecules. CTLs recognize peptide antigens and kill target cells through similar mechanisms as NK cells, including perforin/granzyme–mediated lysis and death receptor pathways. CTLs are characterized by markers such as CD8 and, upon activation, acquire robust proliferative and cytokine-secreting capabilities.

Clinical relevance includes roles in antiviral immunity, tumor immunosurveillance, and pregnancy. Therapeutic strategies aim to enhance killer cell activity, such as adoptive transfer of NK or CAR-NK cells and cytokine-based activation, as well as modulation of inhibitory pathways to boost cytotoxic responses.