Immunology | Myndbook

Acquired Immunity

Innate Immunity

Physical Barriers

1. Skin; problematic with desquamation (shedding of skin) > may lead to organism dispersal (E.g chickenpox)

2. Anatomical curvatures of the GIT; problematic with age as structures may be altered

3. Mucociliary escalators; problematic with smoking & analgaesic agents > as they paralyse

4. Sweat production; problematic as moist enivornment may lead to organism growth within gland

First Line of Defence

Second Line of Defence

Third Line of Defence

Chemical Barriers

1. Lysosomes (tear/saliva)

2. Hydrochloric acids; limited when reduced acidity following a meal

3. Lactobacilli (in vagina); may be out-grown by other bacteria

4. Antibodies (IgA in mucosal layer); may be lysed by bacteria

5. Gut microbiota ("Garden"); may lead to a 'super-infection' or opportunistic infection following antibiotics

Physical Barrier (Lymphocytes & Granulocytes)

Non-specific Immune cells

1. Monocytes (blood) > macrophages (tissue)

2. Neutriphils (blood) > polymorphonuclear cells (tissue)

3. Dendritic cells (phagocytic properties)

4. Natural killer cells

5. Basophils (blood) & mast cells (tissue) > release histamine

6. Eosinophils > release granules onto parasites

Exogenous Immunity

Mediated by bacterial infection > immune system responding with antibodies (unable to go within cells)

- Monocytes detect foreign cell within blood > signal B-lymphocytes (via MHC2) to specifically proliferate with unique receptor to bacterial antigen with T-help cell co-stimulation (T-cell dependant activation) > B cells differentiate into plasma or memory cells > antibody formation

- B-lymphocytes are able to activate/proliferate without the co-stimulation of T-helper cells (T cell independent activation) when LPS, encapsulated microbes, TLR detection,

Endogenous Immunity (Cell-mediated)

Mediated by viral infections > involvement of cytotoxic T cells & T helper cells

- Respond to either APC (TLRs, macrophages, dendritic cells, antibodies etc) or Bodily cells (non-APC like skin, hair cells)

- APC cells can present with MHC1 (inflammatory response) or MHC2 (non-inflammatory response)

- MHC1 antigens signal CD8 receptors (on cytotoxic T cells) > cell lysis & destruction

- MHC2 antigens signal CD4 receptors (on T-helper cells) > B-lymphocyte activation/proliferation > plasma & memory cell formation

Chemical Barrier

1. Interfeuron; signal other cells > "warn them" of imminent attack

2. Complement proteins; punch-holes in cells & coat them = more phagocytic (can also mediate inflammatory process)