Transplant Immunology & Tolerance

By completing this question set, you will be able to classify transplant graft types and explain why HLA matching and crossmatch testing reduce rejection risk. You will differentiate the four types of transplant rejection (hyperacute, acute cellular, acute humoral, chronic) by their timelines, mechanisms, biopsy findings, and treatment approaches. You will identify GVHD from its clinical features and distinguish acute from chronic forms, explain the prerequisites for GVHD, and describe the therapeutically beneficial graft-versus-leukemia effect. You will classify the six types of transfusion reactions by timeline, mechanism, and management, with particular attention to the IgA deficiency → anaphylactic reaction pathway. You will describe central and peripheral tolerance mechanisms, identify immune-privileged sites, and explain how tolerance breakdown leads to autoimmunity through molecular mimicry, epitope spreading, and other mechanisms. Finally, you will connect tolerance gene defects (AIRE, FoxP3, CTLA-4) to their clinical syndromes.