Pathology & Physiology (Subject) / Lectures (Lesson)

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• Cytokines - produced when needed, not stored - polypeptides or glycoproteins of low molecular weight which bind to the receptor of the target cell - generally affect gene transcription via second messengers 
• Pro-inflammatory cytokines + functions 1. TNF-alpha & IL-1 - endothelial adhesion molecules, increase coagulation, stimulate fibroblasts, promote cytokine secretion, systemic effects 2. IL-6 - syetmic effects (pyrexia, acute phase response, haematopoiesis)
• Anti-inflammatory cytokines + function 1. IL-10 - inhibits cytikine secretion, reduces antigen presentation  2. TGF-beta - immunological tolerance, released by myofibroblasts in the context of fibrosis
• Cells of the innate immune system + appearance + function 1. Macrophages  - Function: Antigen presentation (MHC class II complex), Phagocytosis, secretion of cytokines 2. Neutrophils - Function: Phagocytosis, key cells in acute inflmmation (first to be recruited from the bloodstream), granules with antibacterial products in ECM and lumen of phagolysosomes - polymorphonucleated 3. Basophils - resemble mast cells but can't leave bloodstream - polymorphonucleated  4. Eosinophils - particularly recruited in immune reactions mediated by IgE (allergies, parasites)  - polymorphonucleated  5. Mast cells - contain granules with preformed mediators (histamine, proteases, etc.), synthesised eicosanoids (prostaglandins) and cytokines (e.g. eosinophil chemotactic factors)
• Cells of the adaptive immune system 1. Lymphocytes - key cells in chronic inflammation a) B cells - become plasma cells when activated, production of immunoglobulins b) T cells - Helper T cells (CD4+) - secrete cytokines --> command and control - Cytotoxic T cells (CD8+) - kill abnormal cells --> immunosurveillance
• Chronic inflammation (cells) - Plasma cells (B cells) - lymphocytes  - multinucleated giant cells - fibroblasts - macrophages
• Scarring (Fibrosis) - appearance + development 1. Appearance - Macroscopic: red (very vascular) and granular surface (capillary sprouts) - Microscopic: capillaries, (myo)fibroblasts, macrophages 2. Development - scars are produced by granulation tissue (endothelial cells, (myo)fibroblasts, inflammatory cells) which replaces the damaged tissue and matures into a scar (fibrosis)
• Maturation of scars Inflammatory cells leave --> proportion of collagen increases --> new blood supply --> dense fibrous tissue 

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