Hyperacute, acute, and chronic transplant rejection mechanisms and graft-versus-host disease tested on USMLE Step 1.
30 cards · basic cards · AI-written, checked twice. Edit anything.
- What causes hyperacute transplant rejection?
Show answer
Preformed recipient antibodies against donor antigens (e.g., ABO or HLA).- How soon after transplantation does hyperacute rejection occur?
Show answer
Within minutes to hours.- What is the primary target of antibody attack in hyperacute rejection?
Show answer
Vascular endothelium of the graft.- What is the characteristic histologic finding in hyperacute rejection?
Show answer
Widespread microvascular thrombosis with graft necrosis.- What test is performed before transplant to prevent hyperacute rejection?
Show answer
Crossmatch test (recipient serum mixed with donor lymphocytes).- What type of hypersensitivity reaction is hyperacute rejection?
Show answer
Type II hypersensitivity.- How soon after transplantation does acute rejection typically occur?
Show answer
Weeks to months.- What is the main cellular mechanism of acute cellular rejection?
Show answer
Recipient cytotoxic T cells attack donor graft cells.- What is the characteristic histologic finding in acute cellular rejection?
Show answer
Dense mononuclear (lymphocytic) infiltrate in the graft.- What causes acute humoral (antibody-mediated) rejection?
Show answer
Newly formed (de novo) antibodies against donor endothelial antigens.- Is acute transplant rejection typically reversible?
Show answer
Yes, often with increased immunosuppressive therapy.- What type of hypersensitivity reaction is acute cellular rejection?
Show answer
Type IV (delayed-type) hypersensitivity.- How long after transplantation does chronic rejection typically develop?
Show answer
Months to years.- What is the dominant histologic feature of chronic transplant rejection?
Show answer
Vascular fibrosis and graft arteriosclerosis (intimal thickening).- Is chronic transplant rejection reversible with immunosuppression?
Show answer
No, it is largely irreversible.
FlashKeepers