Basic Immunology Flashcards
What cells make up the innate immune system?
neutrophils, monocytes, macrophages, mast cells and natural killer cells
How does the innate immune system detect infection?
pathogen associated molecular patterns (PAMPs) bind toll like receptors
How does the innate immune system detect cell damage?
damage associated molecular patterns (DAMPs) bind to DAMP receptors
Which chemokines and cytokines are released when TLRs and DAMP receptors are activated?
IL-1beta, TNFalpha, IL-6, CXCL8, IL-12
What is the outcome of the complement system?
the membrane attack complex
How is the complement system activated?
either via the classical pathway, the lectin pathway or the alternative pathway
What is the central junction for all the complement pathways?
C3 convertase
How is the classical complement pathway activated?
antigen-antibody binding
How is the lectin complement pathway activated?
mannan-binding lectin binds mannose on pathogen surfaces
What happens to patients that have a deficiency of C1q, C1r, C1s and C4?
immune complex deposition in tissues leading to glomerulonephritis
What happens to patients that have a deficiency of late complement pathway?
can’t make a membrane attack complex so are immunodeficient and get infections particularly to neisseria meningitidis
What happens to patients that are deficient in C1 esterase inhibitor?
hereditary angioneurotic oedema
What is complement induced HUS?
either genetic or autoimmune disease leading to deficiency of complement regulatory proteins which causes renal failure and organ failure
How do you differentiate complement induced HUS from TTP and infection induced HUS?
ADAMTS13 normal, shiga toxin negative
How do you treat complement induced HUS?
eculizumab - a monoclonal antibody which blocks cleavage of C5 - however this means that can’t make MAC so need to be vaccinated against neisseria
Where do you find MHC I?
on all nucleated cells
Where do you find MHC II?
on antigen presenting cells, dendritic cells, B cells and macrophages
What is the role of the thymus?
in late fetal life all T cells go to the thymus where thymic epithelial cells express most self peptides - if there is binding then those T cells undergo apoptosis
What is AIRE?
a transcription factor in thymic epithelial cells for expression of self peptides
What is required for T cell clonal proliferation?
need antigen to presented by MHC, need second activating signal (CD40, CD80, CD86)
What is the role of CD4 T cells?
recruit and activate innate leukocytes
What is the role of CD8 T cells?
kill targeted cells/microbes by granzyme and perforins
What are the 4 types of CD4 T cells?
TH1, TH2, TH17 and T reg
What is the role of TH1?
activate macrophages, induces B cells to produce opsonising antibodies
What is the role of TH2?
activates B cells to make neutralising antibodies
What is the role of TH17?
protects against intracellular pathogens e.g. candida
What is the role of Treg?
secretes cytokines (IL-10 and TGF beta) with immunosuppressive properties
What is the role of IgM?
complement activation
What is the role of IgG?
opsonisation and phagocytosis, complement activation
What is the role of IgE?
immunity against helminths, mast cell degranulation
What is the role of IgA?
mucosal immunity
