citotoxicitat

Citotoxicitat, also known as cytotoxicity in English, denotes the capacity of a substance, cell, or immune effector to kill or damage cells. It is a central concept in toxicology, pharmacology, and immunology. In chemical and drug contexts, cytotoxic agents cause cell death by mechanisms such as DNA damage, oxidative stress, disruption of membranes, or interference with essential metabolic processes. The resulting cell death can proceed via apoptosis, necrosis, or necroptosis, depending on the agent and cell type.

In immunology, cytotoxicity refers to the targeted killing of compromised or foreign cells by immune effectors, notably cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. These cells release perforin and granzymes to induce apoptosis in target cells, or engage death receptors such as Fas. Antibody-dependent cellular cytotoxicity (ADCC) is another pathway wherein antibodies bound to target cells recruit effector cells to kill the target.

Measurement of cytotoxicity is performed with in vitro assays that quantify loss of target viability or release of cytoplasmic contents. Classic methods include the chromium-51 release assay; modern approaches use LDH release, MTT/WST-1/MTS, resazurin, or flow cytometry-based viability assays.

Applications and implications: Many anticancer therapies rely on inducing cytotoxicity in tumor cells, either directly through cytotoxic drugs or indirectly through immunotherapies that enhance immune-cell cytotoxicity. Off-target cytotoxicity contributes to adverse effects in chemotherapy and radiotherapy, underlining the need for selectivity and dosing control.

Etymology: from Latin cytis, cell, and toxicus, poison. Note on terminology: “cell killing” is a common informal descriptor in both toxicology and immunology.