L1&2: Innate & Adaptive Immunity Flashcards
list examples of cell migration
- to sites of infection/inflammation
- from blood to lymph and vice versa
- from primary lymphoid organs to secondary lymphoid organs
- between secondary lymphoid organs
what is chemotaxis?
directional migration of cells up a concentration gradient of chemotactic molecules
What is IL-8 an example of?
a chemo/cytokine produced by macrophages which attracts neutrophils to the site of infection
what are chemokines?
chemoattractant cytokines which play a vital role in how immune cells migrate between immune organs and to sites of infection and inflammation
how many chemokines and how many receptors
47 chemokines and 19 chemokine receptors
what is the difference between alpha and beta chemokines?
the position of 2 cysteines in the protein
where do the cells that express CCR7 migrate to? and in response to which ligands?
cells expressing CCR7 will migrate to the lymph nodes in response to secretion of CCL19 and CCL21
What are the 3 main components of the inflammatory response?
- blood supply increases to the area affected.
- capillary permeability increases (allows exudation of serum proteins in surrounding tissue like Abs, complement)
- leukocyte migration
describe the sequence of events of leukocyte migration to the site of infection (hint: phased appearance)
- Neutrophils appear first (IL-8 produced by macrophages attracts them), they peak after 1-2 days, 10 fold increase in their production in the bone marrow, one way migration
- APCs (like macrophages, DCs) are there from the start, numbers increase, migrate to LNs to present antigens
- CTLs and Th cells arrive days later after their activation by APCs in the LNs & spleen
- B lymphocytes arrive days later, small no. as the antibodies do their work
can the innate system identify bacteria or viruses?
yes, but not very specifically, can recognize LPS
what is the component of the pathogen the immune system sees?
antigen
how much antibody does a health 70-80kg adult produce daily?
2-3g Ab (2/3 of which is IgA)
primary function of antbodies?
bind to its antigen
direct effector function of Ab?
neutralise bacterial toxins, neutralise viruses
secondary function of Ab?
activation of complement, lysis of bacteria and some viruses, opsonisation of pathogen
what is opsonization?
covering the pathogen with antibody to tag it for phagocytosis by macrophages/neutrophils, which have Fc receptors
name general barriers or immune defences
skin, fatty acids, lysozyme, acid, commensal bacteria
innate immunity response to Gram negative bacteria
Gram -ve bacteria are susceptible to lysis by complement
innate immunity response to Gram +ve bacteria
they have a cell wall of peptidoglycan which makes them sensitive to degradation to lysozyme
what do PRRs recognise?
PAMPs (pathogen associated molecular patterns)
what happens in the proteasome?
proteins in the cell are degraded into short peptides and loaded onto MHC molecules, shipped out through the ER/Golgi to be presented to the outside world on the surface of the cell
what must peptides be bound to and on where in order to be recognized by T cells
must be bound to MHC on either APCs or infected cells
what do NK cells recognise?
the absence of MHC on the cell surface
what do cytotoxic T cells recognise?
non-host peptides loaded onto MHC
what do macrophages and other phagocytes do with the virus-infected cell they have ingested?
they degrade the proteins in the proteasome, load them onto MHC through the ER/Golgi apparatus and present these foreign peptides to the T cells
what gene fusions produce the TCR
V, D, J, and C genes fusions
each T cell has a unique _ which recognizes a certain _
each T cell has a unique TCR which recognizes a certain antigen
what cells are MHC class I expressed on?
all nucleated cells
what cells are MHC class II proteins expressed mainly?
mainly on antigen presenting cells
besides foreign proteins like viral ones, what other cells’ peptides can be displayed on MHC class I
tumour peptides from tumour cells
where are proteins degraded for presentation on MHC class II?
In endolysosomes
perforin is produced by the _ of / and is a _ _.
perforin is produced by the degranulation of CTL/NK cells and is a granule protein
what receptors do phagocytes have which facilitate phagocytosis?
phosphatidylserine residue receptors which bind the exposed phosphatidylserine residues on their surface
where in phagocytes are apoptotic bodies destroyed?
in the phagolysosomes
