An Introduction to immunology (physiology) Flashcards
A protein molecule that binds with high affinity to specific antigens:
Antibody
A substance that can bind to an antibody or T-cell receptor. Can be self or non-self:
Antigen
The specific surface feature of an antigen that binds to the antibody:
Epitope
The process by which cells “expose” or “present” an antigen to other cells of the immune system:
Antigen presentation
Small signalling proteins that regulate the activity of the immune system, by interacting with specific cytokine receptors on target cells:
Cytokines
A substance that binds to a pathogen making it more susceptible to phagocytosis:
Opsonin
A cell type that can internalise substances and microorganisms to inactive/kill them:
Phagocyte
A type of immune cell that contains granules within the cytoplasm. These granules are filled with protein-based signalling molecules, and can be released in response to specific signals:
Granulocyte
Nomenclature system used for the purposes of immunophenotyping cells:
Cluster of differentiation
A protein complex that presents an antigen to other cells of the immune system:
Major histocompatibility complex (MHC)
What are the three arms of the immune system? (6)
•Physical barriers
-Chemical, mechanical and biological barriers.
• Innate immune system
-Pattern recognition receptors, phagocytes, NK cells…
•Adaptive immune system
-T-cells, B-cells and antibodies
Note:Specificity increases as you go down.
What are some of the examples of the physical barriers of the immune system?
Mechanical-Skin, flushing.
Chemical-Peptides, acids and enzymes.
Biological-Commensal flora in various body compartments.
What are active phase proteins?
Proteins secreted by the liver in response to cytokines (IL-1, IL-6 and TNFa) released by pro-inflammatory immune cells.
What are the three acute phase proteins and which role do they each play? (6)
-Serum amyloid A: Recruit immune cells to inflammatory sites and induce enzyme that degrade the extracellular matrix.
-Lactoferrin- Bind to iron in order to reduce free iron to pathogens and tumour cells.
-C reactive proteins- activate complement, induces apoptosis and phagocytosis.
Which two types of antigens are recognised by the pattern recognition receptors in the innate immune system? (2)
Pathogen associated molecular patterns (PAMPs) and Damage associated molecular patterns (DAMPs)
Which receptors recognises PAMPs?
Toll-like receptors (TLR)
What role does the ff cells play in phagocytosis:
1. Neutrophils
2. Macrophages
3. Dendritic cells
4. Epithelial cells
- Eliminate invading microorganisms by intracellular killing.
- Eliminate exogenous pathogens, host-derived molecules and dead cells.
- Induces the adaptive system by presenting antigens to T-cells.
- Eliminates neighbouring dead cells.
What is the role of basophils?
It is involved in the host defence against parasitic worms.
What are the functions of eosinophils? (3)
-Releases proinflammatory mediators in response to various immunoglobulins and cytokines.
-Involved in allergic response.
-Secretes major basic protein (MBP) which increases the permeability of the membrane and can kill parasites.
One role of NK cells?
Secretes enzymes that bore holes in cell membranes of infected cells.
Functions of cytokines? (5)
•Play important role with regards to:
-Inflammation
-Anti-virus activity
-Interleukins
-Inhibition/activation of the immune system
-Chemotaxis
What are the three pathways of complement?
Classic pathway: predominantly results in the formation of the membrane attack complex.
Alternative pathway: results in increased phagocytosis.
Lectin pathway: Regulates inflammation by attracting macrophages and neutrophils.
Explain the role of the C3 convertase enzyme in complement and how the MAC is activated (5)
-The C3 convertase enzyme is produced through alternative mechanisms by the 3 pathways.
-The C3 convertase enzyme cleaves the C3 protein into C3a and C3b.
-C3b is responsible for opsonisation and phagocytosis of pathogens.
-Through a series of biochemical reactions, the C3b is converted into C5 convertase enzyme. This occurs in both the classic and alternative pathways.
-The C5 convertase is responsible for the activation of the Membrane Attack Complex which kills pathogens.
What are the end products for the three complement pathways? (3)
-The alternative pathway results in increased opsonization which leads to increased phagocytosis.
-The classic pathway results in the formation of the membrane attack complex (MAC) which is resp for bacterial lysis.
-The lectin pathway results in the degranulation of mast cells which triggers histamine release.
