Session 15: Overview of immunology Flashcards
Define an antigen.
Any agent capable of binding specifically to components of the immune system, such as the B-cell receptor or antibodies.
Define an epitope.
Specific portion of antigen that binds to the T-cell receptor.
Define an immunogen.
Any agent capable of inducing an immune response.
Give the 4 requirements of immunogenicity.
- Foreignness
- High molecular weight
- Chemical complexity
- Degradability and
interaction with MHC
Define a hapten.
- Substances that fail to induce an immune response in their native form bc of their low molecular weight and chemical simplicity.
Define an adjuvant.
A substance that when mixed w/ an immunogen enhances the immune response against that immunogen.
*used in vaccines to accelerate, enhance and prolong the immune response.
Name the two divisions of the immune system.
- Innate/non-specific
immunity - Acquired/specific immunity
What are the components of the physical barriers of innate immunity cells.
- Skin
- pH of the skin
- sweat
- sebaceous secretions
- Hair
- protects against
mechanical abrasions - prevents contact w/ skin
- Mucosal surfaces
- Respiratory tracts
- Genito-urinary tract
- Gastro-intestinal tract
What is pattern recognition ?
- Immune system contains cell-bound and soluble molecules that recognize "warning" patterns - Patterns can be on invading substances or damaged tissues
Name the two types of patterns recognized by the pattern recognition molecules.
- PAMPs
- pathogen associated
molecular patterns - DAMPs
- damage associated
molecular patterns
Describe toll-like receptors as of the cell pattern recognition molecules.
- Found on numerous cells of the body - Recognises PAMPs and DAMPs - activates cell and elicits inflammatory response
Name the 5 cell-bound pattern recognition molecules.
- Toll-like receptors (TLR)
- NOD-like receptors- all PAMPs
- C-type lectin receptors- fungal elements
- F-met-leu-phe receptors- bacterial pathogens
- RIG-I like receptors- viruses
Name the 2 soluble pattern recognition molecules and describe each.
- COMPLIMENT
- destroys invaders and signals other immune system players that attack is on.
- classic pathway
- alternative pathway
- mannose binding lectin
pathway
*CRP
- c-reactive protein
- produced by liver
- activates compliment
system and promotes
phagocytosis
- acute phase protein
List the four types of cells that belong to the Innate Immune System.
- Phagocytes
- Dendritic cells
- Mast cells, basophils,
eosinophils - NK cells
Describe how phagocytes function in the innate immune system.
Phagocytosis: engulfment of a particle by leucocytes such as macrophages and neutrophils.
Macrophages: - located below surface of areas exposed to the outside world. - function as garbage collectors, antigen presenting cells, or vicious killer
Neutrophils: - foot soldiers: patrol blood vessels and await danger signals - kill invading pathogens: * phagocytosis * respiratory burst * NETs * hydrolytic enzymes
Describe how dendritic cells function in the innate system.
- sample antigens out in the tissue - travel to nearby lymph nodes and present these antigens to B and T-cells, if there's an invasion
Describe how natural killer cells function in the innate immune system.
- Target cells for killing by
“missing self hypothesis” - activating receptors
- inhibitory receptors
- Balance between kill and
don’t kill signals determine
whether NK cells will
destroy a target
Describe how eosinophils, basophils and mast cells function in the innate immune system.
- Defense against parasites, helminths and allergic reactions
What is the primary function of the innate immune system?
Kill invading pathogens
What are the 2 secondary functions of the innate immune system?
- inflammation
- recruit and activate
adaptive IS in case of
failure
Discuss inflammation as a secondary function of the innate immune system.
Characterized by: * vasodilation of local blood vessels * increased capillary permeability * movement of fluid * migration of WBC * swelling * fibrinogen clots wall of the area
- aim: recruit more cells to the site to contain the damage
Discuss fever as a manifestation of inflammation.
- Produced by the release of cytokines called endogenous pyrogens - pyrogens are poduced by cells of innate IS in response to PAMPs and DAMPs - pyrogens stimulate hypothalamus to increase the body temp.
Describe the 2 functions of fever.
1. Generally beneficial for
the host bc most
pathogens grow at lower
temps.
2. Immune cells function
better @ higher
temperatureList the 2 functions of B-cells.
- Antigen presenting cells
- Terminal cells produce
antibodies
Describe MHC in the acquired IS.
- antigen presentation is the main function of the acquired innate system
Describe the processes that occur in MHC class I.
* proteins made inside cell are advertised * all nucleated cells in the body * can be read by NK cells and cytotoxic T-cells
Describe the processes that occur in MHC class II.
* exclusively on antigen presenting cells * external * advertise what's happening outside the cells * present peptides to helper T-cells
Name the two types of T-cells.
Helper T-cells
Cytotoxic T-cells
What is the function of helper T-cells?
Secretes cytokines which recruit and activate other cells of the immune system
What is the function of cytotoxic T-cells?
Kills target cells by means of killer receptors
List the 5 functions of antibodies.
- Neutralization of toxins
- Virus inactivation
- Opsonification
- Activation of complement
- ADCC
