4 Transplantation and Immune Compatibility Free Online FlashCards

What is an allograft?

An allograft is a transplant between genetically different people of the same species.

Why does ABO blood-group compatibility matter in transplantation?

A and B antigens may be present on graft blood vessels, so ABO incompatibility can trigger an immune response.

What role do HLA proteins play in transplant compatibility?

HLA proteins help the immune system distinguish self from non-self. Matching is particularly important in kidney and hematopoietic cell transplantation, though its role varies by organ and allocation system.

What are donor-specific antibodies (DSAs)?

Donor-specific antibodies are recipient antibodies that recognize the proposed donor’s HLA. They may develop after pregnancy, blood transfusion, or a previous transplant.

What does a physical crossmatch test?

A crossmatch tests whether the recipient’s serum reacts with donor cells. A positive result can indicate a high risk of antibody-mediated injury.

How does a virtual crossmatch assess compatibility?

A virtual crossmatch compares the recipient’s known antibody profile with the donor’s HLA type to assess compatibility risk.

What causes hyperacute rejection, and when does it develop?

Pre-existing antibodies bind the graft and activate complement and clotting, causing rejection within minutes to hours.

What are the two main mechanisms of acute rejection?

T-cell-mediated rejection involves recipient T cells attacking graft tissue; antibody-mediated rejection involves donor-specific antibodies and associated tissue injury. The mechanisms can overlap.

What characterizes chronic rejection?

Chronic rejection develops over time through persistent immune injury and scarring. Its effects depend on the transplanted organ.

How does the direction of immune attack in GVHD differ from solid-organ rejection?

In GVHD, immunocompetent donor T cells—classically after an allogeneic hematopoietic cell transplant—attack recipient tissues. In solid-organ rejection, the recipient’s immune system attacks the graft.

What is the purpose of induction immunosuppression?

Induction is stronger treatment given around the time of transplantation to reduce early rejection risk.

What is a common kidney-transplant maintenance regimen?

Maintenance is ongoing combination therapy. A common kidney-transplant approach combines a calcineurin inhibitor such as tacrolimus, an antimetabolite such as mycophenolate, and corticosteroids.