Innate immunity

Mechanical/Physical barrier : skin,ciliary clearance

Chemical barriers : lysozyme, low stomach pH,
mucous membranes, anti-microbial peptides

Biological barriers : normal flora

Anti-viral by type I IFN(alpha and beta) or IFN-I

Accute inflammation

-Local inflammatory response
-Systemic inflammatory response : Interaction of various cytokines
-Acute phase protein: C-reactive protein

Chronic inflammation

Granulomatous inflammation

Interplay between innate and adaptive immunity

Activation of adaptive immunity

T cell activation and differentiation

Th1
-cell-mediated immunity and inflammation
-intracellular pathogens
-autoimmunity
-inflammation

Th2
-antibody-mediated immunity
-extracellular parasites
-asthma, allergy

Characteristic of innate immunity

Rapid/quick response

Non-specific responses

No memory

Recognition of pathogens

Stimuli

PAMPs : derived from components of microorganism

DAMPs : derived from host cell

Pattern recognition receptors (PRRs)

Type of PRRs
- Toll-like receptors (TLRs)
- NOD-like receptors (NLRs)
- RIG-like receptors (RLRs)
- C-type lectin receptors (CLRs)

Tissue immune cells

Intraepithelial lymphocyte (IELs)

Macrophage
-Professional phagocytosis cells
-Professional APCs

Peripheral blood immune cells

NK cells : distinc from T and B cells in that lacks antigen-specificity and recognize on MHC I

Neutrophils: a professional phagocytic cell

Dendritic cells : professional APCs

Eosinophils

Basophils

Monocytes

Humoral substance of innate immunity

Cytokines, mediators, complement system

Phagocytosis

-Professional phagocytes :Neutrophils, Monocytes/Macrophages
-Non-professional phagocytes: Epithelial cells,Fobroblast,Dendritic cells

Phagocytosis event
-Chemotaxis and adherence of microbe to phagocyte
-Ingestion of microbe by phagocyte
-Formation of a phagosome
-Fusion of the phagosome with a lysosome to form a phagolysosome
-Digestion of ingested microbe by enzymes
-Formation of residual body containing indigestible material
-Discharge of waste materials