Immunology Flashcards
Which type of immunity am I describing?
- limited specificity, no memory formed, cellular components are neutrophils, NK cells and macrophages
Innate immunity
What cellular components are involved in adaptive immunity?
B cells and T cells
What is haematopoeisis?
Formation of WBC, RBC and platelets and takes place in the bone marrow
Myeloid progenitor cells develop into myeloid cells such as?
Neutrophils, basophils, eosinophils, mast cells, dendritic cells, macrophages and monocytes
Give examples of epithelial surfaces and their role in the innate immune response
Epithelial surfaces provide a physical barrier
Low pH of skin and fatty acid in sebum inhibit microbial growth
Gut has gastric acid, pancreatic enzymes and mucosal immunoglobulins (IgA), and normal colonic flora which stops overpopulation of microbes
Respiratory tract secretes mucus to trap organisms and cilia transport them to the throat to be coughed up or swallowed into gastric acid
Flushing of urine through urinary tract prevents microbes from adhering to the urothelium
Give examples of phagocytes
Macrophages and neutrophils
What is complement? How many pathways are there?
What is the end product?
Circulating proteins which assist the immune system in killing microbes
There are 3 pathways - classical (activated antibodies to a pathogen), alternative pathway (microbes lacking regulatory protein present on host cells) and the lectin pathway (mannose binding protein)
The end result is the generation of C3 converts which splits into C3 and C3b. Microbes coated in C3b are phagocytosed or killed by the membrane attack complex which punches holes in the microbe.
What are the 4 main ways in which antibodies work?
- Neutralise the biological activity of a vital microbial molecule (eg. toxin)
- Target microbes for phagocytosis
- Activate complement
- Activate cytotoxic immune cells
Which T cells are activated by Class I MHC expressed by all nucleated cells?
CD8+ cytotoxic T cells
Which T cells are activated by Class II MHC expressed by all specific antigen presenting cells such as dendritic cells?
CD4+ T helper cells
Where do B cells and T cells mature?
Both produced in thymus but T cells mature in the thymus and B cells mature in the bone marrow
Do B cells need an antigen to be presented on MHC molecule?
No, they can bind to an antigen directly and then present the antigen to T cells on MHCII class receptor
What happens when a B cell presents an antigen to a T cell?
The T cell gets activated, it helps the B cell mature into a Plasma Cells and memory cells. Plasma cells serve to secrete antibodies which circulate in the serum and mark pathogens for destruction by phagocytes.
Memory B cells ‘remember’ the offending pathogen to be able to mount a quicker immune response next time it is encountered.
What happens when a T cell first encounters a pathogen?
The naive T cell is primed and turned into a mature T cell which causes clonal expansion of the T cells some of which are effector cells and some are memory T cells
What are the different subtypes of T cells? What are their roles?
- helper Tcells (CD4)facilitate the activation of the immune response through cytokines and stimulate division and differentiation of various effector cells (B cells)
- cytotoxic T cells (CD8)– also known as killer or effector T cells. Providecell-mediated immunityby targeting and killing infected cells including cancer cells
- regulatory Tcells– also known as suppressor T cells – play a vital role in limiting the immune response to prevent excessive damage to tissues and organs
- memory T cells“remember” what has happened to allow the immune system to mount a faster, more effective response should the offending organism return
In the immune response, which antibody (unspecific) is first produced and which (specific) antibody is produced later?
IgM is produced first
IgG is highly specific and is produced after
How does the innate immune response differentiate good from bad bacteria?
Using pattern recognition receptors (PRRs) and pathogen associated molecular patterns (PAMPs)
What are examples of PAMPs which the innate immune system (macrophages, neutrophils etc) can recognise on bacteria and respond to?
peptidoglycan, lipopolysaccharide, lipoteichoic acid, fungal wall components (mannan) and flagella proteins
Activation of TLRs and PRRs drive what?
Cytokine production by APCs that increase the likelihood of successful T cell activation
What are the main family of PRRs?
Toll like receptors - these play a vital role in initiation of innate immune response by detecting harmful pathogens.
Which TLRs recognise bacterial and viral microbes
Bacterial: TLR 1,2,4,5,6,9,10
Viral: TLR 3,7,8
Whats the difference between passive and active immunisation? Which provides longer term immunity?
Passive: provided when a person is given antibodies to a disease rather than producing them through his or her own immune system.
A newborn baby acquires passive immunity from its mother through the placenta. A person can also get passive immunity through antibody-containing blood products such as immune globulin, which may be given when immediate protection from a specific disease is needed. The major advantage to passive immunity; protection is immediate, whereas active immunity takes time (usually several weeks) to develop. Protection is not life long, it lasts a few weeks.
Active: results when exposure to a disease organism triggers the immune system to produce antibodies to that disease. Exposure to the disease organism can occur through infection with the actual disease (resulting in natural immunity), or introduction of a killed or weakened form of the disease organism through vaccination (vaccine-induced immunity). Immunity is life long but takes some time to get immunity.
Examples of when artificial passive immunity (pooled IgG against pathogens given) might be needed?
- Individuals with inborn or acquired agammaglobulinaemias
- Exposure to a disease what could cause complications (immune compromised patient exposed to measles)
- When there isn’t time for active immunisation to give protection (pathogen has short incubation time)
- Acute danger of infection
- Anti-toxins and anti-venins
does passive immunity create memory cells?
No
