<prompt> All of the following are mediators of inflammation except:Tumour necrosis factor-a TNF-aInterleukin-1MyeloperoxidaseProstaglandins  <response>: Ans. is c i.e., Myeloperoxidase Myeloperoxidase is not an inflammatory mediator. It is an enzyme of neutrophil which catalyzes the conversion of Cl, Bf, and T, and SCN to the corresponding acids HOCl, HOBr etc.. These acids are potent oxidants and help in destroying the invading organisms.Mediators of inflammationMediators are derived either from plasma or from cells.Plasma derived mediators - These are present in plasma in precursor forms that must be activated usually by a series of proteolytic cleavage.Cell derived mediators - Cell-derived mediators are sequestered in intracellular granules that need to be secreted e.g. histamine in mast cells or are synthesized de novo.Summary of Mediators of acute inflammationMediatorSourceVascular leakageChemotaxisOtherHistamine serotoninMast cell, platelets- BradykininPlasma substrate-PainC3aPlasma protein via liver-Opsonic fragmentC5aMacrophagesLeucocyte adhesion,ProstaglandinsMast cells, from membrane phospholipidProteinate other mediators Vasodilatation, pain, feverLeukotriene B4Leucocytes-Leucocyte adhesion, activationLeukotriene C4, D4 e4leucocyte, Mast cells-Bronchoconstriction, vasoconstrictionOxygen metabolitesleucocytesEndothelial damage, tissue damagePAFLeucocytes, mast cellsBronchoconstriction, leucocyte primingIL-1 and TNFMacrophages, other-Acute phase reactions, endothelial activationChemokinesLeucocytes, others-Leucocyte activationNitric oxideMacrophages, endotheliumVasodilation cytotoxicity Role of mediators in different reactions of inflammation. VasodilationProstaglandins Nitric Oxide HistamineIncreased VascularVasoactive aminespermeabilityC3a and C5a Bradykinin leukotrienes C4, D4, F4 PAF Substance P Chemotaxis, leucocyte recruitment and activationC5a leukotriene B4 Chemokines II-1, TNF Bacterial productsFeverII-1, TNF ProstaglandinsPainProstaglandins, BradykininTissueNeutrophil and macrophagedamageLysosomal enzymes oxygen metabolites Nitric oxide 