Lecture 1 Flashcards
What are the four main types of pathogens? give an example for each
Viruses (SARS-CoV-2, Influenza, HIV, poliovirus)
Bacteria (Staphylococcus aureus, Mycobacterium tuberculosis, Vibrio cholerae)
Fungi (Candida albicans)
Parasites (Trypanosoma, Leishmania, Roundworms, Tapeworms)
What do innate immune cells recognise on the pathogens and how?
Recognise PAMPs (Pathogen associated molecular patterns)
Recognised by PRRs (pattern recognition receptors)
Give three examples of phagocytosing cells
- Macrophages
- Neutrophils
- Dendritic cells
What is the innate immune system?
non-specific, rapid first line of defence
Give an example of humoral innate immune response
Complement system
Give an example of a cell mediated innate immune response
Neutrophil phagocytosing and destroying pathogen
What is the adaptive immune response?
specific and effective against certain pathogen. memory cells form for more rapid response if reinfection occurs.
Give an example of humoral adaptive immune response
Clonal selection and clonal expansion of specific B-lymphocyte to secrete antibodies
Give an example of a cell mediated adaptive immune response
Cytotoxic T-lymphocytes
How are the PRRs of innate immune response encoded?
Germ line encoded (already present from birth)
How are BCRs and TCRs of the adaptive immune response encoded?
encoded by genes created during ransom DNA re-arrangements to give variability in receptors.
What is clonal selection?
The binding of an antigen to an individual B or T cell that triggers clonal expansion of the cell to produce a population with the same antigen specificity in order to increase the number of cells responding to the pathogen and form memory cells
How does the antigen binding to B and T cells differ?
B cells can bind directly to the antigen
Where as T- cells can only bind to an antigen that is being presented to them by an APC
What is the difference between MHC I and MHC II molecules?
MHC I is present on the surface of all nucleated cells. requires CD8 co-receptor
MHC II is present only on the surface of antigen presenting cells. Requires CD4 co-receptor
True or false: innate immunity has memory?
True, it has some memory in the form of innate lymphoid cells (ILCs) and trained immunity in macrophages - little known about innate memory - most of the memory is in the adaptive immune response.
Give some major cell types of the innate immune response
Phagocytes
Innate lymphoid cells (E.g. natural killer cells)
granulocytes (neutrophils, eosinophils, and basophils)
Antigen presenting cells (macrophages, dendritic cells)
Give some major cell types of the adaptive immune response
T-cells
B-cells
(activated by APCs)
Where do all immune cells develop?
develop in bone marrow from haematopoietic stem cells
What are the two main cell lineages of immune cells?
myeloid and lymphoid
What are the primary lymphoid organs?
Bone marrow and the Thymus
What is different about the maturation of T-cells?
They are produced in the bone marrow and migrate to the thymus as double negative cells - it moves through the cortex and medulla, where it experiences different microenvironments that allow differentiation into single positive cells.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2861282/
What are the secondary lymphoid organs?
spleen and lymph nodes
What is the main role of the secondary lymphoid organs?
location for interaction between B and T cells with antigens to become activated, expand in numbers, and differentiate into effector cells.
- lymph nodes are responsible for filtering the lymph
- the spleen filters blood (functions against blood-borne pathogens)
What is Mucosa associated lymphoid tissue?
example of another secondary lymphoid organ - it is a large, dispersed and important lymphoid tissue to protect vulnerable mucosal surfaces (gut, lungs, nasal passages)
- where antigen sampling occurs in small intestine and immune responses are initiated
- epithelia overlying (MALT) contain membranous (M) cells which transport antigenic matter across the mucosal membrane to initiate immune responses.
https://pubmed.ncbi.nlm.nih.gov/10381862/
how is the lymph node arranged in terms of zones?
B and T cells separated into distinct microenvironments
- B cell = cortex
- T cell = paracortex
How do antigens enter the lymph nodes?
afferent vessel
how do naive lymphocytes enter the lymph nodes?
High endothelial venule (HEV)
how do lymphocytes exit the lymph nodes?
efferent vessel
What are the three main compartments/components of the spleen and the cells they contain?
Red pulp = red blood cells
White pulp = white blood cells
marginal zone (boarders white pulp) = macrophages and B cells
What are cytokines?
small protein messengers that send signals between immune cells and generate a response by signal transductiong
Give some responses generated by cytokines?
differentiation, proliferation, apoptosis
what are chemokines?
class of chemoattractants that are small protein messengers that send signals with the main effect of causing movement of target towards source.
