Immunosupression Flashcards
how does treating allergy with antigen in desensitisation regimes work
it diverts the response from TH2 to TH1 to produce IgG instead of IgE
what method other than desensitisation is used to treat allergy
specific inhibitors to block effects of inflamatory mediators produced by mast cells
why is autoimmune disease hard to control
because response not recognised until its well established
how is autoinflamatory disease treated
cortico steroids, cytotxic drugs
why does treatement of autoinflammatory disease often lead to opportunistic infection
because treatment is non specific so entire immune system is compromised
which molecules are primarily responsible for graft rejection
MHC molecules
what are the two ways in which alloantigens are recognised
the donor APCs migrate to lymphnodes or allogenic proteins are taken up by host APCs and presented to Tcells
how rapidly does hyperacute rejection occur
24hrs
what is the cause of hyperacute rejection
preexisting antibodies from a previous transplant or blood transfusion against MHC and blood type specific antigens
what is the result of hyperacute rejection
complement and blood clotting cascades block the blood vessels of the graft
what occurs in graft versus host rejection
mature t cells in the donor tissue recognise host tissues causing inflammatory response
what sort of immunosupressive drugs are synthetic analogues of cortisol
corticosteroids
how do corticosteroids work
they bind intracellular receptors and are then transported into the nucleus where they control transcription
what are the effects of corticosteroids
anti inflammatory
which inflammatory cytokines are reduced by corticosteroids
IL-1 TNFa IL-3 IL-4 and IL-5
how does decreasing the expression of adhesion molecules reduce inflammation by corticosteroids
wbcs are less likely to migrate from blood vessels
how does increasing the expression of endonucleases as a result of corticosteroids have an inflamatory effect
increases apoptosis in lymphocytes and eosinophils
how do the immunosuppresive drugs azithrioprene and mycophenolate work
interfere with dna synthesis
how does the immunosuppresive drug cyclophosphamide work
it alkylates dna
Which type of fungus is cyclosporin A derived from
Tolypocladium inflatum
which bacteria is tacrolimus derived from
Streptomyces tsukubaensis
which bacteria is rapamycin derived from
Streptomyces hygroscopicus
how do cyclosporin A, tacrolimus and rapamycin work
they bind immunoflins and interfere with clonal expansion of lymphocytes
how does cylcosporin A block t cell proliferation
inhibits the Ca2+ activated enzyme calcineurin
which bacterial cytotoxic drugs reduce the expression of cytokines such as IL-2 which is a growth signal for t cells
cyclosporin A and tacrolimus
what are the negatives of bacterial cytotoxic drugs
indescriminant, toxic to kidneys and expensive
how does rapamycin cause t cells to die
it blocks the late stages of activation
why is antibody therapy preferable to immunosupressive cytotoxic drugs
they interfere in a non toxic, more specific manner
how do depleting antibodies work
trigger destruction of lymphocytes by macrophages and NK cells
how do non depleting antibodies work
they block the function of a target protein without killing the cell
how can antibodies be used in organ transplant
perfusion of the organ before transplantation with Abs that react with APCs targetting them for destruction
how can Ab therapy be used to treat autoimmune disease
to modify and reduce the immune response
which antibodies can be used in treatment of RA
anti-TNFa antibodies eg infliximab, etanercept
anti-IL-1 eg Anakinra
what is the role of IFNg in TH1 response
activate macrophages and drive inflammatory response
which sort of Thelper response is autoinflamatory disease related to
th1
how does skewing the response from IgE to IgG and IgA in allergy reduce allergic symptoms
these Igs bind the allergen rather than binding mast cells and causing degranulation
how can TH2 cells be primed to produce IL-4 and TGF-b without activating TH1 or antibody response
with peptide allergens
how does EBV cause immunosuppresion
encodes a homologue of IL-10 which inhibits TH1 lymphocytes, reducing IFNg production
which cells does HIV infect
CD4+ Tcells, DCs and macrophages
how does HIV kill the cells it infects
direct viral killing, increased susceptibility to apoptosis, killing by CD8+ cells which recognise infected CD4+ cells
how does mycobacterium leprae cause immunosuppression
suppresses cell mediated immunity (lepromatus leprosy) or cell mediated antibacterial response
