Flashcards in asts.mycrowdwisdom.com Deck (14):
What are T cells?
lymphocytes that recognize MHC antigens on the surface of cells
How are T cells selected in the thymus?
positively: binding of thymus epithelium gets selected for
negatively: too much affinity for self-MHC
What are the accessory molecules involved with T cell activation?
CD4 - helper T
CD 8 - cytotoxic T
CD 28 binding with B7 on APC does what?
stabilizes and strengthens activation triggered by TCR binding
CTLA4/CD152 binds with B7 to do what?
downregulates response; controls activation achieving a homeostasis
What is allograft rejection?
immune mediated graft injury; often defined by time or mechanism (cellular, immune)
ddx: recurrent dz
Rejection can be multifactorial:
T cell, antibody, cytokine
Naive cells require what to cause an effective rejection reaction?
Lymphoid tissue (memory cells do not)
What is heterologous immunity?
Immunity to one antigen can confer immune reactions to other antigens
Trauma can increase naive T cell conversion to memory T cell. What does this mean for the surgeon?
Surgical technique can affect transplant rejection.
How does antibody mediated rejection cause injury?
antibodies to donor antigens cause inflammatory reaction and coagulation (hyperacute rejection; should be screened for)
What is the centerpoint of multiple means of complement activation?