Mechanisms of Cell Injury

Accumulation of free radicals occurs also in pathologic conditions as inflammation. Killing microbes by neutrophils and macrophage occur by oxygen dependent and oxygen independent mechanisms.Oxygen dependent mechanism is the main mechanism for killing microbes.It causes rapid burst of ROS due to rapid activation of an oxidase called NADPH oxidase and in this process oxygen will be reduced to superoxide anion. Superoxide anion is then converted to hydrogen peroxide by dismutation reaction.Hydrogen peroxide can also be reduced to hydroxyl radical. The ozorophilic granules of neutrophils contain an enzyme myeloperoxidase MPO which in the presence of a halide as cl convert H2O2 to hypochlorite OCL which a potent antimicrobial agent that destroy microbes by halogenation or by oxidation. Neutrophils form nitric oxide from arginine and nitric oxide can act as a free radical and can also be converted a highly reactive peroxy nitrite anion ONOO.These freee radicals destroy the microbes.

[@medicalacc3801]

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[@mharithadj1]

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