Block A Flashcards
True/False: The innate immune system is specific
False, its non-specific. Aquired is specific
True/False: Innate immune system is inherited
True, does not require prior exposure like the adaptive does
What cellular responses first occur in the innate immune system
Phagocytosis, Inflammation responses and antimicrobial protein production
In the innate immune system, what’s the importance of receptors (3 marks)
-recognising invaders
-recruiting different cells
-producing proteins that facilitate destruction of proteins
Phagocytes engulf and destroy particles by ________
endocytosis
Name 5 professional phagocytes
-neutrophils
-monocytes
-macrophages
-mast cells
-dentritic cells
How do phagocytes move
Chemotaxis
What are sentinels
Resident phagocytes that most tissues contain
Name the role of neutrophils
First responders in inflammation
Name the role of macrophages
Highly phagocytic, engulf many pathogens
Name the role of mast cells
Produces histamine which causes inflammation
Name the role of dentritic cells
Act as a bridge between innate and adaptive immune systems
Describe the process of phagocytosis (6 marks)
-recognition and ingestion of the pathogen
-phagosome formation
-phagosome and lysosome fusion
-digestion of phagosome
-waste
-antigen presentation
Describe how inflammation is stimulated
-Phagocytes are activated by Pattern Recognition Receptors (PRRs)
-PRRs recognise Pathogen Associated Molecular Patterns (PAMPs)
-Once PRRs recognise PAMPs, cytokines and chemokines are released by cells, these cause inflammation and a fever
-Histimine causes vasodilation
-Vasodilation attracks neutrophils to clear pathogens and summon lymphocytes (important in adaptive immunity)
Explain the 2 antimicrobial proteins that are important in the innate immune system
-interferon-inhibits viral replication inside host cells
-complement-kills microbes without phagocytosis, causes microbes to burst
What are PAMPs
They are a set of microbial molecules that share a number of patterns that alert immune cells to destroy intruding pathogens
What are DAMPs
A set of patterns associated with damaged cells
Describe how cytokines can instruct a target cell to die
Can instruct a target cell to increase or decrease enzyme activity so it dies.
Name the role of chemokines
They attract immune cells to the site of infection
How do B and T cells form
They both develop in the bone marrow from haematopoietic stem cells. Immature B cells are found in the bone marrow, mature B cells move to the lymphoid organs. T cells move to the thymus.
Explain how B cells get a B cell receptor (BCR)
Re-arrangements of the immunoglobulin occur within the cell so that an unique BCR receptor is formed on the immature B cells
What is an Immunoglobulin
Aka an antibody, composed of 4 linked polypeptides, 2 long heavy chains, 2 short light chains
What is the role of IgM and IgG (2 marks)
-The most abundant Ig in mammals
-Provides specific immunity against viruses and bacteria
What is the role of IgE (1 mark)
-Defend against parasites and allergic responses
What is the role of IgA (2 marks)
-Secreted in the lining of GI tract and respiratory tract to protect locally
-Major antibody found in breastmilk
Which region on an antibody binds to an antigen
Variable region
Whats an epitope
The binding site on a antigen
Describe how a B cell activates.
-BCR is activated by antigens and by cytokines from a Helper T Cell
-Once activated, B cells proliferate into plasma cells that produce antibodies and some memory cells
-Memory cells are dormant waiting for a future attack of same pathogen
What is opsonisation
When a pathogen is marked for phagocytosis
How does the body prevent autoimmunity
-an APC presents an immature T cell with MHC
-T-cells which react moderately are positively selected, recieving signals for survival
-those that recognise the MHC too strongly or too little are sent signals for apoptosis, and negatively selected
Whats a Major Histocompatibility Complex (MHC)
A group of genes that code for proteins that recognise and present peptides from pathogens on the surface of a cell
Describe how an antigen is broken down (3 marks)
-antigen is taken up into intracellular vesicle
-endosomal proteases are activated to degrade antigen into peptide fragments
-vesicle containing peptides fuses with vesicle containing MHC class II molecules
State the role of MHC I molecules
They are found in the membrane of almost all cells
Which MHC class does CD4+ go with
MHC II
Which MHC class does CD8+ go with
MHC I
What purpose does CD4+ T cells serve
CD4+ activates other immune cells and is a T helper cell
What purpose does CD8+ T cells serve
CD8+ kills infected cells and other pathogens and are killer cells
Which cytokines to memory T cells require, to promote survival
IL-7 and IL-5
Name and state the role of small proteins secreted by virus-containing cells
Interferons, these are released by infected cells and activate other immune cells to fight the virus.
Which antibody activates complement
IgM
The antibody molecule is held together by ___ bonds
disulfide
In clonal selection of B cells, which substance is responsible for determining which cells become cloned
Antigen
Which ONE antibody is the most important in protecting against gut infections?
IgA
Which ONE antibody is most abundant in body fluids?
IgG
Which ONE antibody is predominantly present in breast milk and colostrum?
IgA
Which one of the following exists as dimer in secretions via J-chain?
IgA
How do B cells swicth the class of antibodies they secrete (2 marks)
-Helper T cells secrete cytokines
-that cause gene rearrangement in the B cell.
