Introduction to Transplantation

UNOS (United Network of Organ Sharing)

Private nonprofit that manages the U.S. organ transplant system

OPTN (Organ Procurement and Transplantation Network)

Public-private partnership linking all professionals in the donation/transplant system

SRTR (Scientific Registry of Transplant Recipients)

Private contractor for statistical and epidemiological analysis of transplants/allocation

CMS (Centers for Medicare and Medicaid Services)

Establishes transplant conditions since it's a major payer

AST (American Society of Transplantation)

Provides guidelines, resources, advocacy, and support

National Organ Transplant Act

Created the Organ Procurement and Transplantation Network; centralized organ procurement and donation

Types of organ donation

Living and deceased

Deceased donation organs

Kidney, Liver, Heart, Lung, Intestine, Pancreas

Brain Death

Comatose, no brainstem reflexes, no spontaneous breathing = legally dead

Cardiac Death

Withdrawal of life support; limited time window after heart stops

Living donation organs

Kidney, partial liver

Living donation pros

Shorter wait time; better/faster graft function

Living donation cons

Donor (especially relatives) can't be caregiver immediately; small risk of post-op complications

Immunogenicity (Least → Most)

Liver → Kidney → Heart → Pancreas → Lung → Skin → Bone Marrow → Intestine

Blood type incompatibility

Incompatible blood = immediate rejection

Blood type A

RBC antigen: A; Plasma antibody: Anti-B; Can receive A or O

Blood type B

RBC antigen: B; Plasma antibody: Anti-A; Can receive B or O

Blood type AB

RBC antigens: A and B; Plasma antibodies: None; Universal recipient

Blood type O

RBC antigens: None; Plasma antibodies: Anti-A and Anti-B; Universal donor

Human Leukocyte Antigen (HLA)

6 alleles, 3 from each parent

Class I HLA

HLA-A, HLA-B; works with cytotoxic CD8 T cells

Class II HLA

HLA-DR; works with helper T cells

Panel Reactive Antibody (PRA)

Tests for preformed antibodies to known HLA types

High PRA value

Harder to match; indicates high % of incompatible donors

Antibody sources

Pregnancy, blood transfusion, prior transplants

Donor liver requirements

ABO compatible, size match, living vs deceased, bile duct vs hepatojejunostomy anatomy considerations

Phases of immunosuppression

Induction, Maintenance, Rejection

Too much immunosuppression

PTLD (Post-transplant lymphoproliferative disorder); Opportunistic infections

Too little immunosuppression

Cellular rejection (T cells); Antibody-mediated rejection (B cells)

Immune function over time

Early post transplant: most immunosuppressed and infection prone; Later: improves but remains below normal permanently

Pediatric dosing strategies

Bodyweight-based, BSA-based, age-based, allometric scaling

Pediatric liver transplant indications

Congenital cause, cholestatic disease, metabolic disease, acute liver failure

Inactivated vaccines

Pre-transplant >2 weeks; post-transplant >3 months

Live vaccines

Pre-transplant >4 weeks; post-transplant avoid

Hepatitis B Core Antibody (HBcAb)

Indicates exposure to HBV

Hepatitis B Surface Antibody (HBsAb)

Indicates immunity to HBV

Hepatitis B Surface Antigen (HBsAg)

Indicates infection with HBV

HBsAb and HBsAg relationship

Cannot be positive for both simultaneously