CLASP Immunology Flashcards
Where do allergen-specific B cells encounter the allergen?
primary follicles of secondary lymphoid follicles
What MHC molecule do B cells present peptides in?
MHC-II
What is the function of IL-4 secreted by Th2 cells?
triggers class switching in activated B cells
What are the functions of IL13 and IL5 produced by Th2 cells?
promote recruitment, activation and survival of eosinophils
What substances do mast cells/eosinophils release?
histamine; tryptase and heparin
What pro-inflammatory cytokines do mast cells/ eosinophils produce?
TNFa and IL4
What position should you put a patient with anaphylaxis in?
lie patient flat and raise legs
What is the dose of adrenaline given for anaphylaxis?
IM dose of 1:1000 (500mcg)
When does type III hypersensitivity reactions occur?
excess of antigen causes immune complexes
What is the difference in antigen between type 2 and type 3 hypersensitivity?
type 2: bound to cell surface; type 3: soluble antigen
What is the function of C3a in type 3 reactions?
mediates induction of granule release from mast cells
What is the function of C5a in type 3 reactions?
recruitment of neutrophils in to the tissue
What are the 3 killing mechanisms of neutrophils?
phagocytosis; degranulation and NETs
What chemical is involved in phagocytosis?
superoxide hydrogen peroxide
What chemicals are invovled in degranulation?
lysozyme; NADPH oxidase; myeloperoxidase
What are NETs
neutrophils extracellular traps which are structures of DNA that kill and tap microbes
What type of T cells are invovled in the initial steps of type 4 reactions?
CD4 Th1 cells
What cytokine do CD4 Th1 cells release in type 4 reactions?
IFN gamma
What is the fcuntion of IFNgamma?
enhance macrophage activity and promote further inflammation and recruitement of other cells eg CD8
How do cytotoxic T cells destroy cells?
peptide/MHC-I manner
What type of drugs can cause false positives in skin prick testing?
monoamine oxidase inhibitors and TCAs
What are the typical signs of small vessel vasculitis?
purpura; vesiculobullous lesions; urticaria; glomerulonephritis; alveolar haemorrhage; cutaneous extravascular necrotising granulomas; splinter haemorrhages; scleritis/episcleritis/uveitis
What are the typical signs of medium vessel vasculitis?
cutanoeous nodules; ulcers; livedo reticularis; digital gangrene; mononeuritis mutliplex; microaneuryms
What are the typical signs of large vessel vasculitis?
limb claudication; asymmetric BPS; absence of pulses; bruit; aortic dilatation
Give examples of large vessel vascultides?
takayasu arteritis; GCA
Give example of medium vessel vasculitis?
PAN; kawasaki
Give examples of vasculitis type 3 hypersensitiity?
SLE; PAN
Give examples of vasculitis which are type 4 hypersensitibity?
GCA; takayasu
Where does inflammation in the vessels in takayasu start?
in the adventitia and moves toward intima
What are the immunological features of steroid use?
lymphocytopenia; neutrophilia; secondary immunodeficiency
What are the endocrine features of steroid use?
DM; HT; increased appetitie and weight gain; adrenal cortex suppression
What are the skin/soft tissue features of steroid use?
cushingoid appearance; abdominal striae; acne; hirsutism; oedema; increased risk of skin cancer
What are the neuro features of steroid use?
neuropathy; pseudomotor cerebri/ IIH
What are the ophthalmic features of steroid use?
cataracts; narrow-angle glaucoma
What are the MSK features of steroid use?
oseopenia; AVN; myopathy
What are teh CVS features of steroid use?
HT
What type of hypersensitiity is cryoglobulinaemiac vasculitis?
type 3
What mediates the damage in cryoglobulinaemic vascultiis?
complemetn
What is the function of RF in RA?
predicts extra-articular features
What are the psychiatryic effects of acute steroid use?
insomnia; agitation; depression/anxiety; psychosis
What are the GI effects of actue steroid use?
GI haemorrhage
how do steroids cause GI haemorrhage?
inhibit phospholipase A2 which converts cell membrane phsopholipis into arachidonic acid- reduced LTs and PGs
What activates complement in the classical pathway?
Fc portion of antiobdy
Which type of antibody is best at activating complement?
IgM- pentamer
Which antibodies can activate complemetn?
IgM and IgG
What complemetn binds to the Fc region of hte heavy hcain?
C1
What is C4b2a known as?
C3 convertase
What part of C1 binds to antibody?
C1q
What must happen for C1q to become firmly fixed?
cross link at least 2 antibody molecules before firmly fixed
What does the binding of C1q cause?
activation og C1r which activates C1s
What is the function of C1qrs?
cleaves C4 into C4a and C4b; and C2 into C2a and C2b
What is C4bC2aC3b known as
C5 convertase
What happens in the alternate pathway?
bacterial, fungal and viral cells surfaces bind C3 and factor B
What is the C3 and factor B cleaved by?
factor D
What does cleavage by factor D procue?
C3bBb
What is the function of C3bBb?
C3 convertase