Lec 1 - Basic Immunology Flashcards
(19 cards)
Compare the Innate and Adaptive Immune System
Innate; broad specificity, not affected by prior contact (do not get an enhanced response if already come into contact with pathogen), quick response for initial infection
Adaptive; v specific, affected by prior contact, long response time
Both primarily involve leukocytes and soluble factors
give 4 examples of large surfaces that act as barriers to infections
- keratinised skin (v rare for bacteria to directly infect the skin, infection occurs once skin has been breached eg burn, wound)
- gastrointestinal and respiratory tract (both v large mucosal surfaces - susceptible to infections)
- urogenital tract (close contact between individuals required for transmission)
give 2 examples of physical barriers
- tight junctions between epithelial cells that line the mucosal layer
- cilia that physically move mucus and any pathogens contained w/in mucus
give 3 examples of chemicals that stop infection
- fatty acids (low pH) on the skin
- lysozyme secreted onto mucosal surfaces
- low pH enzymes eg pepsin
how does the microbiome help prevent infection?
growth of commensals in the gut etc prevent the growth of pathogenic bacteria
Where are leukocytes derived from and give the 2 main lineages that come from them?
pluripotent stem cells from bone marrow
create myeloid cells (macrophages, neutrophils) and lymphoid cells (TH cells, B cells, NK cells)
Name the 2 types of phagocytes that exist
mononuclear phagocytes
neutrophils
Describe neutrophils
- exist in the blood
- short lived (unless infection established)
- fast moving
- lysosomes secrete enzymes eg H2O2
Describe the 2 locations where mononuclear phagocytes exist and describe them
- in blood = monocytes
- in tissues = macrophages
- live for a long time (months-years)
- can stimulate the adaptive immune response
Where are mast cells found?
- tissues (like MAcrophages) underlying the mucosal layer
What are NK cells effective against and how do they work?
- effective against intracellular viruses
- release their granules and induce apoptosis
Name the 3 types of soluble proteins that exist
defensins, interferons, complement
Describe defensins
- small, +vely charged peptides that can insert themselves into and disrupt bacterial membranes
What types of cells produce interferons?
any cell that has been infected with a virus
give the 3 results following IFNa/b release
- signals nearby cells to resist virus replication
- signals NK cells to kill infected
- increase in MHC-I receptors and antigen presentation to stimulate adaptive response
What is the name of the MAIN component of the complement system and give the name of the structures that form when it is cleaved?
C3
cleaved into C3a and C3b
Describe the 3 pathways that can lead to complement activation
- MB Lectin pathway (lectins bind to mannose sugars on surface of bacteria)
- antigen:antibody complexes
- pathogen surfaces eg LPS
Describe the 3 outcomes of complements activation
- opsonisation (C3b coat pathogens and phagocytes with C3b receptors are recruited and phagocytosis)
- recruits other members of immune system (chemoattractants eg C5a released, recruit neutrophils and anaphylatoxins, C3a, stimulate mast cells to promote inflammation)
- cell lysis (C9 forms polymers, hollow tubes forming membrane attack complex)
Describe what occurs in the LOCAL (inflammation) and SYSTEMIC (fever) responses.
Local;
increase in bloody flow to capillaries, dilation of capillaries, increase in permeability
ALL allow neutrophils and interferons etc to escape into tissues (site of infection)
Systemic;
acts on hypothalamus to increase body temp in effort to kill bacteria
