Immunology Flashcards
the ability of T cells to recognize non-self MHC alleles
allorecognition
T cell recognizes unprocessed allogeneic MHC molecule on graft APC
direct allorecognition
presentation of processed peptide of allogeneic MHC molecule bound to self-MHC
indirect allorecognition
minutes to hours after transplant
preformed anti-graft Ab
primarily Ab-mediated indicating prior exposure to donor antigens; complement involved in immune complex formation that causes tissue damage
rapid, irreversible damage
hyperacute graft rejection
1-2 weeks after transplant
primarily T cell mediate in response to non-self MHC
requires T cell priming, clonal expansion, differentiation
monitor graft function and use immunosuppressants at earliest sign of rejection; reversible/controllable
repeat episode are common
acute graft rejection
months after the transplant
cell mediated and Ab mediated immunity
fibrosis and scarring associated with tissue remodeling, loss of graft function (slow infiltration of immune cells)
targets recipient and donor vessels causing tissue damage
difficult to manage and immunosuppression is often ineffective
chronic graft rejection
immune response that results from T cells in the donor bone marrow mounting an immune response to recipient tissue
graft versus host disease
immune response that results from allogeneic bone marrow transplant in which donor T cells attack host leukemia cells
graft versus leukemia
optimize chance of graft survival
Ab to known panel of HLA antigens are used to probe HLA profile of donor and recipient
serology
optimize chance of graft survival
proliferation test of donor and recipient lymphocytes in tissue culture; proliferation in response to allogeneic cell exposure is measured with radioactive thymidine that is incorporated into DNA
mixed lymphocyte reaction
optimize chance of graft survival
more accurate for identifying genotypes, routine for HLA typing
PCR for HLA gene allotypes
the immune system surveys self-tissues for malignant cells and decreases cancer development
immunosurveillance
selective pressure may result in development of tumors that are less immunogenic over time
immune editing
because of immune editing, tumors that ultimately develop have evolved mechanisms to evade an effective immune response
immune evasion
negative co-stimmulatory molecule expressed on T cells after activation and on T reg cells which can interfere with T cell activation
interacts with B7 with higher affinity than CD28
therapeutic targeting to promote T cell activation is associated with autoimmune inflammatory complications
CTLA-4
negative co-stimulatory molecule expressed on T cells after activation
induces signaling events that inhibit TCR stimulation
therapeutic blockage promotes tumor specific immune response
PD-1
normal immunodeficient in newborns
decreased Ig levels during the window between decrease in maternal Ab (IgG via placenta) and when infant begins to produce Ab
Decreased/altered T cell immunity in newborns may also affect humoral response
Transient hypogammaglobulinemia
severe defect in immune function resulting in increased susceptibility to bacteria, viruses, fungi, and protozoa including opportunistic infections
always associated with a defect in T cell function but may also involve B cells and NK cells
prenatal screening is being widely instituted (look for DNA fragment byproduct of somatic recombination = TCR excision circles = TREC)
Severe Combined Immunodeficiency (SCID)