Module 2: Branches of the Immune System Flashcards
Immune barrier
-physical
-soluble
-cellular
Inflammation of innate immunity function
-1st immune response event following the breach of a physical barrier by a pathogen
Pattern recognition of innate immunity definition
-recognized general patterns not specific for any one antigen
Physical barrier
-made of every structure located at the interface between the inside and the outside of the body
Cellular barrier
-made of various different cells
Soluble barrier
-made of macromolecules which contribute to the mediation of an innate response
Physical components of the physical barrier
-skin
-mucous membranes covering respiratory, gastrointenstinal, urinary and reproductive tracts
Chemical components of the physical barrier
-tears and saliva
-gastric acid
Cells of the cellular barrier
-neutrophils
-macrophages
-dendritic cells
-natural killer cells
Neutrophils
-most common
-phagocytes that engulf pathogens
-recruited to the site of infection by resident macrophages
Macrophages
-phagocytes that patrol the body to engulf pathogens
-contribute to tissue repair and present antigens to other immune cells such as T cells
Dendritic cells
-phagocytes that are often in contact with external environment
-present antigens on cell surface
-major link between innate and adaptive immunity
Natural killer cells
-recognize abnormal cells and destroy them such as tumours and viruses
-bind to target cell and release chemicals lysing the cell membrane
The soluble barrier parts
-complement system
-cytokines
Complement system components
-30 soluble proteins that circulate in the blood
-activated by presence of extracellular pathogens
Complement system functions
-inflammation
-phagocytosis
-membrane attack complex
What are cytokines
-small proteins secreted by various immune cells in response to a number of different stimuli
-chemical mediators for cell to cell communication
Cytokines function
-autocrine
-paracrine
-endocrine
-pro-inflammatory
-anti-inflammatory
Inflammation characterization
-redness
-swelling
-heat
-pain
Inflammation purpose
-bodys attempt at self protection and to localize and eliminate the pathogen in an effort to stop it from spreading and remove damaged tissue
Major events of inflammation
-breach
-vasodilation
-permeabilization
-extravasion
-phagocytosis
Breach
-pathogens breach the physical barrier
Vasodilation
-increase in blood vessel diameter
Permeabilization
-allows accumulation of excess fluid called exudate
-exudate: pro inflammatory cytokines and complement proteins that attract key cells to site of infection
Extravasion
-chemotactic factors released by cells during the vasodilation induce the recruitment of more immune cells to the site of infection by way of chemotaxis
Phagocytosis
-macrophages and dendritic cells engulf pathogens
PRR
-capable of recognizing repeated molecular patterns of pathogens
Molecular pattern
-pathogen associated molecular patterns (PAMPs) which are expressed on surface of or found inside pathogens
PAMP
-molecules associated with groups of pathogens that are recognized by immune cells which include functional structures of a pathogen & repeated sequences of protein, glycoprotein, lipoprotein, amino acids etc
DAMP
-molecules released by stressed cells undergoing necrosis which are host biomolecules, indicate damage to the body, and initiate an inflammatory response
Toll-like receptor
-class of PRRs
-upon activation they initiate transcription of genes encoding for inflammatory cytokines, chemokines, costimulatory molecules
-they contribute to the activation of the innate immune cells which increase ability of phagocytes to engulf pathogens
Toll like receptor function
-sense presence of an infection through recognition and engulf by the phagocytic cell
-after engulfing, the cell will present pieces of the pathogen on its cell surface
-antigen presenting cell will also increase its production of costimulatory molecules
-an immunocompetent naive t cell will bind to the peptide and initiate an adaptive immune response
Cells involved in phagocytosis
-neutrophil
-macrophages
-dendritic cell
Steps of phagocytosis
-attachment
-ingestion
-fusion
-digestion
-release
Adaptive immune system main function
-specificity
-diversity
Components of the adaptive
-humoural immunity: b cells and antibodies
-cell mediated immunity: t cells
B cell characteristics
-mature in bone marrow
-b cell receptor
-antibody factory
Subsets of B cell
-plasmocyte: effector cell
-memory b cell: memory cell
T cell characteristics
-mature in the thymus
-t cell receptor
-cytotoxic activity or help the activation of immune response
Subsets of T cell
-CD4 helper: effector cell, helps the activation of the adaptive immune response
-CD8 cytotoxic: effector cell, kills infected cells
-memory: memory cells, express TCR and CD4 or CD8 on their cell surface
To induce cell mediated immunity
-Th cells will differentiate into Th1
To induce humoural immunity
-Th cells will differentiate into Th2
What is an antibody
-large y shaped protein that is highly specific
-also called an immunoglobin
Where do antibodies come from
-surface antibodies: membrane bound on b cells
-soluble antibodies: secreted by b cells
Basic structure of human immunoglobins
-2 heterodimeric proteins that are held together by disulfide bonds
Chains that immunoglobins contain
-2 light chains
-2 heavy chains
-2 antigen binding regions
-1FC region
Immunoglobulins
-IgM
-IgG
-IgA
-IgE
-IgD
IgM
-first antibody to be formed in an immune response
-activates complement system
IgG
-coats pathogens to promote phagocytosis
-only one that can cross placental barrier
IgA
-first line of defence
-predominant antibody class located in mucosal membranes
IgE
-produced in excess during allergic reactions
-has a role in immunity against certain parasites
IgD
-found in large quantity on surface of mature B cells
-function is unclear but thought to play a role in B cell development
Example of PAMP
-lipopolysaccaride (LPS)
-peptidoglycan
-flagellin
-viral nucleic acids
Example of PRR
-TLR4
