Immunity

Innate: Immediate, Natural, always present(innate), Block and rapidly eliminate microbes.

Adaptive: Slow and specialized, acquired/specific, expansion and differentiation of lymphocytes in response to microbes before it can provide an effective defense. 

Lymphocytes: specific recognition of Antigens.

B Lymphocytes: Mediators of Humoral immunity.

T Lymphocytes: Mediators in cell-mediated immunity.

Antigen Presenting Cells: Capture of antigens for a display to Lymphocytes.

Dendritic cells: initiation of T cell responses.

Macrophages: effector phase of cell-mediated immunity

Follicular dendritic cells: the display of antigens to B lymphocytes in humoral immune responses.

Effector Cells: T lymphocytes, Macrophages, Granulocytes.

T Lymphocytes: activation of phagocytes, killing infected cells.

Macrophages: Phagocytosis and killing of microbes.

Granulocytes: Killing microbes.

Generative lymphoid organs: bone marrow (B lymphocytes and myeloid cells), Thymus (T lymphocytes).

Peripheral Lymphoid organs: Lymph system, skin, lymph nodes and vessels, spleen.

Pathogen associated Molecular Patterns: innate cells express receptors that recognize molecular structures produced by microbial pathogens.

Damage Associated Molecular Patterns: Innate receptors can be activated by damage to cells.

Pattern recognition Receptors: Receptors that recognize PAMPS and DAMPS)

Innate immune cells recognise a PAMP or DAMPà Capture, engulfment and destruction or Display of antigen to other cells.

Innate cells: Macrophages and dendritic cells that can phagocytose microbes.

Phagocytosis: recognition and attachment of PRR on the cell surface, Engulfment, Killing, and degradation.

Phagocytosis degradation: Reactive O species, nitric oxide, lysosomal enzymes.

Adaptive immune system capable of recognising 10^7-10^9.

PRR recognition: Humoral immune response or cell-mediated immune response.

Humoral immunity: mediated by antibodies produced by B cells, antibodies recognise microbial antigens neutralise their infectivity and target microbes for elimination (mainly extracellular).

Cell mediated immunity: Mediated by T cells and their produced cytokines (Mainly intracellular).

Immunologic Memory: subsequent exposures to the same antigen are faster, larger, as each exposure to an antigen generates long-lived antigen-specific memory cells, return the immune system to homeostasis faster.

Innate immune system: Fast as microbes can multiply fast, release phagocytes, inflammatory cytokines and interferons/antivirals, Cytokines.

Adaptive Immune system: takes 6-7 days.

Innate immune system recognises PAMPS and DAMPS with PPR’s

Epithelial Barrier: Physical barrier, Produce antimicrobial chemicals (direct toxicity or activation of other Leukocytes), Intraepithelial T cells recognise small number of common microbial structures (Cytokine Production and Phagocyte activation)

Phagocytes: Neutrophils and monocytes, Macrophages (recruited from  blood into infected tissues in response to signals from sentinel cells).

Dendritic cells: Express many PRR, versatile sensor of PAMPS and DAMPS, capable of triggering and directing adaptive T cell mediated immune response(present In epithelia and most tissues)(  uptake & transport of antigens to lymph nodes, upregulation of costimulators, production of cytokines).

 Natural Killer cells: Kill infected cells via granule exocytosis of perforin and granzyme proteins adjacent to target cells, Produce Cytokine interferon (IFN)-y to increase the capacity of macrophages to kill phagocytosed bacteria.

Soluble components: recognize microbes and/or promote innate/adaptive responses

Complements: Culminate in the production of peptides that stimulate inflammation (C3a, C5a) and polymerized C6-C9 which form membrane attack complex.

cytokines: Signalling molecules that aid cell to cell communication in immune response and stimulate movement of cells toward sites of inflammation, infection and trauma.

Inflammation: Bring leukocytes and plasma proteins to the site of infection or tissue damage, eliminate the cause and initiate healing.

Inflammation symptoms: Redness, Heat , Swelling  (Leakage of cells and fluid into tissues), Pain (Increased nerve sensitivity due to chemical mediators).

Inflammatory process: Offending agent recognized by host cell/molecules > produce chemical mediators, Leukocytes and plasma proteins recruited from circulation > activated to destroy and eliminate offending substance, Reaction is controlled and terminated damaged tissue repaired.

resolution of inflammation: normal permeability, Drainage of fluid & proteins into lymph, Pinocytosis into macrophages, Phagocytosis of apoptotic neutrophils,  Phagocytosis of necrotic debris, Disposal of macrophages.

Type 1 Interferons: Bind onto uninfected cells inducing the expression of enzymes that block viral replication > turns on an antiviral state.

Infected cell: produce type 1 interferons that bind onto uninfected cells.