Immunology Flashcards
What cell is associated with the innate immune response?
neutrophils.
What are the tissue resident innate immune cells?
macrophages, mast cells, NK cells, dendtritic cells.
Which cell kills virally infected and cancer cells?
NK cells.
Which cells mediate the allergic response
eosniphils.
Which cells play a key role in the defence against parasites?
mast cells.
How do macrophages kill?
phagolysosome and toxic reactive oxygen and nitrogen species.
What do pathogens express and how do innate immune cells recognise these?
pathogen: PAMPs (pathogen associated molecular pattern)
immune cell: PRRs (pathogen recognition receptors)
What is the acute phase response?
a change in plasma concentration of specific proteins in response to inflammation.
What plasma proteins are involved in the acute phase response?
CRP (acts as opsonin)
manganese superoxidase
fibrinogen
what are the cell adhesion molecules that neutrophils bind to?
selectins
ICAM1/VCAM1
what is involved with selectins and neutrophils?
neutrophils bind weakly to selectins via integrins. selectin mediated rolling of neutrophils occur.
what is involved with ICAM1/VCAM1 and neutrophils?
neutrophils bind strongly to ICAM1/VCAM1 via integrins. DIAPEDISIS occurs (squeeze through endothelial cells)
How do neutrophils kill?
release of Anti-microbial proteins. produce toxic reactive oxygen species. release NETs (neutrophil extracellular traps - act as opsonins)
What is the complement system?
a family of proteins produced by the liver. potent enzymatic cascade and amplification loop.
how is the complement system activated?
1) classic complement pathway: antibodies (IgG, IgM) binding to antigens
2) alternative complement pathway: C3b
3) Lectin pathway
which protein forms the membrane attack complex? how does it kill?
C5b. osmotic lysis.
Which complement protein is a key mediatiator in the complement system and also acts as an opsonin?
C3
What is the function of B-cells?
produce antibodies (plasma cells) produce memory B-cells
what do CD4+ T-cells do? CD8+ T-cells?
CD4+ = Helper T-cells. Key regulators of the adaptive immune response, help activate other cells. CD8+ = Cytotoxic T-cells. kill virally infected cells.
How do CD8+ cells kill?
1) Fas
2) release of perforin (both activate caspases)
Which gene codes for antibodies and how is variation achieved?
segmented genes. random rearrangement of the segemnted genes.
What constitutes the primary lymphoid tissue?
bone marrow: site of all leukocyte development
Thymus: site of T-cell maturation
What tissue is secondary lymphoid tissue?
lymph nodes + spleen
How does an antibody bind to an antigen?
via Fab —> epitope (on antigen)
what is a dendritic cell? how does it do this?
professional antigen presenting cells. express antigen specific peptides on MHC moleculs
in the secondary lymphoid tissue, which cells are found in “B-cell zones”?
Stromal cells. “trap” opsonised antigens
what are the 2 types of MHC molecules? where are they found and who do they present to?
class I MHC: expressed on all nucleated cells. present antigen to cytotoxic T-cells (CD8+) class II MHC: expressed only on antigen presenting cells (dendritic, macrophages, B-cells). present antigen to CD4+ helper T-Cells
What is the germinal centre and where is found?
found in secondary lymphoid tissue. site of B-cell proliferation and differentiation
describe IgG
most abundant immunoglobulin in plasma. pass through placenta, providing protection to babies.
describe IgM
largest of the antibodies. 1st antibody produced in infection.
describe IgA
responsible for mucosal immunity.
describe IgE
responsible for the allergic response.
What are Peyer’s patches? where are they found?
organised lymphoid tissue. found in the ileum.
What special epithelial cell lines Peyer’s patches?
M cells (have a characteristic membrane ruffle)
what is the IELs found in epithelium called?
(intra-epithelial lymphocytes) CD8+ cytotoxic T-cells
What is selective IgA deficiency associated with?
coeliac disease.
what is type 1 hypersensitivity?
immediate hypersensitivity (allergy). IgE mediated.
what is type 2 hypersensitivity?
direct cell killing/cytotoxic hypersensitivity. this is achieved via activation of the complement system (classical pathway only: IgG/M–>antigen) forming the membrane attack complex (C5b).
eg. ABO blood incompatibility
what is type 3 hypersensitivity
immune-complex mediated. eg. farmers lung, bird fanciers lung
what is type 4 hypersensitivity?
delayed type hypersensitivity. (T-cell mediated). non-caseating granuloma formation. eg. TB, sarcoidosis, Rheumatoid arthritis.
