Week 2 - Innate and adaptive immunity Flashcards
Define complemen
The process by which antibodies and phagocytic cells clear microbes and damaged cells from an organism, promoting inflammation and attacking the pathogen’s cell membrane
Name the 3 complement pathways and briefly outline each
Classical - antibody-antigen complex (C1 complement protein binds to complex, initiating the process)
MB-Lectin - Lectin binding to surfaces (made of carbohydrates)
Alternative - C3 protein differentiates between normal cells because of presence of sialic acid on terminal sugars and bacterial cells due to presence of manose terminal sugars on human cells.
Describe the 3 processes that can happen post complement activation
Recruitment of inflammatory cells - e.g neutrophils, monocytes, lymphocytes, T cells, mast cells NK cells
Opsonisation of pathogens - marking of pathogens for phagocytosis e.g addition of antibodies to make them sticky and easy to phagocytose
Killing of pathogens - 4 complement proteins form a membrane attack complex which creates a hole in cell wall of bacteria. Cell bursts
How would you simply describe complement
A cascade of reactions by proteins in the serum
Describe the structure of the neutrophil
Multi-lobed nucleus
What percentage of the WBCs are neutrophils
50-70%
What does a high percentage of WBCs imply
Presence of infection
What is the main role of neutrophils
Phagocytose and digest pathogens - phagosomes collect pathogens from surface and fuse with phagolysosome. Phagolysosome contains digestive enzymes which kill the pathogenW
What else to neutrophils release
Soluble mediators such as cytokines, chemokines and complement
Which line of defence are neutrophils
FIrst
Name some primary neutrophil granules found in neutrophils
Lysosomes
Myseloperodinase
Natural proteases
Acid hydrolyses
Name some secondary neutrophil granules
Lysozome
Collagenase
Lactoferrin
Cathespin B
What term describes the way that neutrophils are attracted towards and the pathogen in question
Chemotactic
What is another example of chemotaxis in action other than when moving towards pathogen
Identification of tissue damage
Name and describe the 4 stages that relate to the way that innate cells stop and enter the infected tissue
Rolling Adhesion -
E-selectin on surface of endothelium is identified by a protein on innate cell. Innate cell therefore slows down and attaches loosely
Tight binding -
Chemokine IL-8 is transcytosed across the endothelial cell. The receptor on the innate cell recognises the IL-8 chemokine and binds. Meanwhile, a stronger bond is produced between the LFA-1 and the ICAM-1 molecule
Diapedesis -
The innate cell pushes apart the tight junctions and moves into tissue
Migration -
The innate cell follows the source of the IL-8 chemokine, taking it to the site of infection
In what way can the macrophage better grasp bacteria
They can reorganise their actin structure to form pseudopodia which engulf bacteria that are then ingested into the cell
What is the main process that macrophages found in the tissue carry out
Retaining homeostasis - i.e digesting all the dead/dying cell material after apoptosis
Which cells are involved in inflammation
Those that derive from maturing monocytes
What are the primary lymphoid organs
Thymus and the bone marrow
What are the secondary lymphoid organs
Lymph nodes
Spleen
What are concentrated in lymph nodes
Antigens
Where is the site of immune response initiation
The lymph nodes
Where do naive T cells identify antigens and pass this information to B cells
The lymph nodes
What are the two types of adaptive immunity
Cell-mediated and humoral
Which cells are involved in the innate immune response (6)
Mast cell
NK cell
Basophil
Neutrophil
Eosinophil
Monocyte/macrophage
Which cells are involved in the adaptive immune response (2)
T lymphocyte
B lymphocyte
Where in lymph nodes are T cells found
Cortex
Where in the lymph nodes are B cells found
Follicles
Describe the humoral immune response
An extracellular attack by antibodies caused by B cells which originate from the bone marrow
Describe the cell-mediated immune response
An intracellular attack by T cells which mature in the thymus
What is the B cell receptor composed of
An antibody
What is thought to make lymphoma such a common cancer
The instability of T and B cell receptor regions since the genetic code has to randomly change in order to cover the vast number of possible antigens
How is autoimmunity prevented in the primary lymphoid organs
Lymphocytes go through education to eliminate any self antigens
Roughly how many times daily do T cells and B cells circulate the lymph nodes
3 times per day
What are the 3 roles of the T helper cells
To tell B cells to make antibodies
To tell cytotoxic T cells to kill other cells
To direct inflammatory responses in tissue
What is the role of the cytotoxic T cell
To recognise and kill cells
In order for T helper cells to work, what 3 requirements must be met
Antigen presentation in the context of MHC
Surface molecule costimulation
Production of cytokines
Which MHC must be associated with the antigen in T helper-antigen presenting cell complexes, in order for it to activate T cells
MHC II
Which MHC is associated with cytotoxic T cells
MHC I
What does the V region of the antibody refer to
The variable region
What does the C region of the antibody refer to
Constant region
What is the other name given to antibodies (in the context of haematology)
Immunoglobulins
What 2 components are responsible for humoral immunity
Antibodies and b cells
What is the region of antigen called that the antibody attaches to
The epitope
Descrribe 4 effects that antibodies can have on pathogens
Opsonisation - making the pathogen sticky, therefore marking it for phagocytosis
Neutralisation - antibody binds to virus and prevents it from entering it’s own receptor, therefore it can no longer replicate and DIES
Compliment activation - by the classical pathway
Drive inflammation - via the complement cascade, inflammatory cells are recruited
Which fragment of the antibody binds to the antigen
The top right variable region
Which region of the lymph node is known as being the B-cell region
Follicle
Which region of lymph node is the T-cell region
Cortex
Name the monomer antibodies
IgD
igE
IgG
Name the dimer antibody
IgA
Name the pentamer antibody
IgM
Functional characteristic of the IgA antibody
Most prevalent in secretions
Functional characteristic of the IgD
Present on all B-cells
Functional characteristic of IgE
Parasitic infections and type 1 sensitivity
Functional characteristic of Ig G
The most abundant antibody and can cross the placenta
Functional characteristic of IgM
Largest and present on all B-cells
What is the first antibody to be produced upon infection
IgM
