sejthalált

Sejthalál (cell death) refers to processes that lead to the systematic disintegration and removal of cells. It can be accidental, due to overwhelming injury (necrosis), or regulated, by which cells actively execute a death program (regulated cell death, RCD).

Apoptózis (apoptosis) is the best-characterized form. It involves intrinsic pathways triggered by cellular stress or extrinsic death receptor signaling, leading to activation of caspases and orderly dismantling without immediate inflammation. The intrinsic pathway engages mitochondria and Bcl-2 family proteins; the extrinsic pathway involves receptors such as Fas and TNFR family members, with caspase-8 acting upstream.

Other regulated forms include necroptosis (RIPK1/RIPK3/MLKL), ferroptosis (iron-dependent lipid peroxidation), and pyroptosis (gasdermin-mediated lysis), as well as autophagic cell death (where autophagy contributes to demise under certain conditions).

Necrosis is typically uncontrolled, causing membrane rupture and inflammatory response. The balance between survival, repair, and death is essential for development, tissue homeostasis, and immune function.

Cells that die are typically cleared by phagocytes in a non-inflammatory manner in apoptosis; necrotic debris can provoke inflammation.

Studying cell death informs cancer therapy, neurodegeneration, ischemia, and infectious diseases. Detection methods include morphological assessment, TUNEL assay, Annexin V staining, and caspase activity measurements.

Terminology: "cell death" is an umbrella term; specific modalities include apoptosis, necroptosis, ferroptosis, pyroptosis, autophagic cell death, among others. The field is evolving as new pathways are discovered.