INFLAMMATORY MEDIATORS

• Inflammatory mediators are of 2 types-

1. Cell derived mediators (present in cells)
2. Plasma derived mediators (synthesized in liver)

Cell Derived inflammatory mediators

 

I) Vasoactive amines-

II) Arachidonic acid metabolites (Eicosanoids)

• Most potent mediators of inflammation.
• They are formed by 2 pathways-

A) Via cyclo- oxygenase pathway- includes

B) Via- lipooxygenase pathway-

    

III) Lysosomal components- 2 types

 A) Granules of neutrophils- 3 types

1. Primary granules (azurophil granules)

• Develop at promyelocytic stage.
• More destructive
• These are-

1. Myeloperoxidase (MPO)
2. Cathepsin
3. Non- specific collagenase

2. Secondary granules (specific granules)

• Develop at myelocytic stage.
• These are-

1. Lactoferrin
2. Lysozyme
3. Type IV collagenase
4. Vitamin B12 binding proteins

3. Tertiary granules (C- particles)

• Involved in chemotaxis
• Contains gelatinase

IV) Platelet activating factor (PAF)

    

V) Cytokines

• They are soluble polypeptide.
• Source- lymphocytes & monocytes.
• They are highly specific.
• Important cytokines are-

a) Interleukines

1. IL1- fever
2. IL4- anti-inflammatory
3. IL6- synthesis of acute phase proteins

b) Tumour necrosis factor (TNF)

• TNF- α- acute inflammatory, septic & shock, systemic inflammatory response syndrome & cachexia.

c) INF- γ- granuloma formation 

VI)  Chemokines

• Action- leukocyte movement, chemotaxis

1. Alpha chemokines (C-X-C)- IL-8
2. Beta- chemokines- Ecotaxin, RANTES, MIP1- alpha
3. Gamma- chemokines- lymphotactin 

VII) Nitric oxide-

• Derived- endothelial cells
• Now synthsized from arginine amino acid
• Action- Vasodilation, anti platelet aggregation, microbicidal action

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