Transplant Immunology

Xenograft

A tissue transplant from one species to a different species (e.g., pig heart valve to human)

Autograft

A tissue transplant from one location to another on the same individual

syngeneic graft (isograft) 

A tissue transplant between genetically identical individuals (e.g., identical twins)

Allograft

A tissue transplant from one individual to another of the same species but with different genetic makeup

A kidney transplant from a deceased, unrelated human donor to a human recipient is classified as a:

Allograft

Which of the following transplant types has the lowest risk of rejection?

Autograft

Which molecule is the primary reason that transplanted tissues are recognized as “non-self” and rejected by the recipient’s immune system?

Major Histocompatibility Complex (MHC) molecules

A kidney transplant is rejected because the recipient’s T cells recognize donor MHC molecules on graft cells as foreign. What is this process called?

Direct allorecognition

Which of the following best describes indirect allorecognition in transplant rejection?

Recipient antigen-presenting cells process donor MHC peptides and present them on self-MHC to recipient T cells.

A transplant patient suffers an organ rejection within hours after the procedure. What type of rejection occurred?

Hyperacute

A transplant patient on a follow-up visit to his physician is noted to have progressive fibrosis and scarring with narrowing of the vessels leading to the transplanted organ. What type of rejection is occurring?

Chronic

A patient awaiting a kidney transplant has already been HLA typed and matched with a potential nonrelated donor. Before proceeding, the transplant team needs to determine whether the recipient has any donor-specific antibodies that could immediately destroy the graft. Which test should be performed next?

Complement-dependent cytotoxicity (CDC) crossmatch

Which of the following is true?

In direct allorecognition, the recipient T cells bind and respond directly to foreign HLA proteins.

To detect HLA antibodies in a patient:

reagent lymphocytes are incubated with patient serum.

The detection of which antibody is important to continue testing for after a solid organ transplant?

Antibodies to donor-specific antigens

Which reagents would be used in a donor–recipient crossmatch test?

Recipient serum and donor lymphocytes + rabbit serum complement

Which statement best describes the mechanism of graft-versus-host disease?

Donor T cells attack recipient tissues

A 12-year-old receives a stem cell transplant for leukemia. Four weeks later, she develops a diffuse, itchy rash, abdominal pain with watery diarrhea, and elevated liver enzymes. What is the most likely diagnosis?

Graft-versus-host disease

Which laboratory test is performed immediately prior to transplantation to ensure no donor-specific antibody is present?

crossmatch test