cytolysis

Cytolysis (cell lysis) results when the plasma membrane is ruptured, resulting in osmosis-induced swelling and cell death. (see cytotoxicity)

Cytotoxic lymphocytes (CTLs) are important agents of cytolysis. Cytotoxic cells are considered essential for the elimination of oncogenically or virally transformed cells, but they are detrimental when mediating autoimmune disease or graft rejection.

Tables  Fc receptors  Immune Cytokines  Immunoglobulins

tags [Immunology][cytolysis][cell+death]

cytotoxicity

Cytotoxic agents are toxic to cells:
● Cytotoxic physical agents
___ ● thermal (excessive heat or cold)
___ ● irradiation

● Cytotoxic drugs and chemicals have cytolytic, carcinogenic, mutagenic and/or teratogenic potential. Direct contact may cause tissue irritation, ulceration, and necrosis.
___ ● antineoplastic and immunosuppressive therapeutic agents
___ ● free radicals
___ ● strong acids and alkalis
___ ● secreted digestive enzymes and antimicrobials – lysozyme, phospholipase, defensins
___ ● secreted cytolytic molecules • FasL, granzymes, granulysin, perforin
___ ● phagocytosis-promoting opsonins – C3b of complement cascade, pulmonary surfactants

● Cytotoxic cellular immune responses
_ ● Antibody-dependent cell-mediated cytotoxicity (ADCC) is mediated by antibody-marking
_ ● Complement-dependent cytotoxicity (CDC) is mediated by the complement system (opsonin-induced phagocytosis performed by macrophages and neutrophils, anaphylatoxin induced histamine release by basophils and mast cells).
_ ● Lymphocyte-mediated cytotoxicity ('LMC') requires is independent of antibody-marking and the complement system

__ ● killer cells
___ ● non-specific 'attack' cells – eosinophils (IgE, CD67), macrophages (IgG, CD14), K cells (IgG), LAK cells (IL-2 activated cytolysis cells, lymphokine-activated killer cells), NK cells (CD16, CD56)
___ ● natural killers cells (NK) of innate immune system – have activating receptors and killer inhibitory receptors (KIR) – secrete cytolytic granzymes and perforin ('LMC')
___ ● natural killer T cells (NKT) – have αβ TCR plus some of the cell-surface molecules of NK cells – respond to glycolipid antigens presented by the cell-surface molecule CD1d (ADCC) – secrete IFN-γ (Th1 cytokine) plus IL-4 and IL-13 (Th2 cytokines)
___ ● cytotoxic T cells • (CD8 +) Tc matures into CTL (killer T cells) following activation (ADCC)
___ ● phagocytic cells engulf pathogens, often after pathogen coating by opsonins (CDC)

Tables  Fc receptors  Immune Cytokines  Immunoglobulins

tags [Immunology] [cytotoxicity] [cell death]