Transplantation: HLA, Solid Organ, and Hematopoietic Stem Cells

Comprehensive vocabulary flashcards covering the biological, clinical, and pharmacological aspects of tissue and organ transplantation, HLA nomenclature, and Graft-Versus-Host Disease.

Genetic Variation

One of the two primary problems in transplantation, representing the difference between the donor and the recipient.

HLA Chromosomal Location

Found on Chromosome $6$ at band $21$ ($6p21$).

Histocompatibility Antigens (HLA)

Molecules that allow T cell discrimination of self vs non-self and present peptides to T-cells for recognition and elimination.

Graft Versus Host Disease (GVHD)

A condition where immune cells of the donor target the foreign cells of the recipient.

HLA Allotype

Represented by the first $2$ digits of a unique HLA antigen name.

HLA Subtypes

Represented by the $3\text{rd}$ and $4\text{th}$ digits of a unique HLA antigen name.

MHC Class I

Major histocompatibility complex consisting of the $A$, $B$, and $C$ regions.

MHC Class II

Major histocompatibility complex consisting of the $D$ region, including $DR$, $DQ$ ($DC$), and $DP$ ($SB$).

Crossmatch

A procedure where donor B cells are mixed with recipient serum to check for preformed antibodies.

Autograft

A graft transferred from one position to another in the same individual (e.g., skin, hair, or bone).

Syngraft

A graft transplanted between different but identical recipient and donor, such as monozygous twins.

Allograft (Homograft)

A graft between genetically different recipient and donor of the same species.

Xenograft (Heterograft)

A graft between individuals of different species, such as a pig heart valve to a human heart.

Cornea

The least immunogenic transplant tissue.

Bone Marrow

Considered the most immunogenic transplant tissue.

Hyperacute Rejection

A humoral-mediated rejection occurring within minutes, caused by preformed cytotoxic antibodies to donor antigens.

Accelerated Rejection

A cell-mediated rejection occurring within $2-5$ days due to previous sensitization to donor antigens.

Acute Rejection

A cell-mediated rejection occurring within $7-21$ days caused by the development of an allogeneic reaction to donor antigens.

Chronic Rejection

Rejection occurring later than $3$ months post-transplant involving cell-mediated mechanisms or immune complex disorders.

Corticosteroids

Drugs that reduce inflammation by inhibiting macrophage cytokine secretion.

Cyclosporine and Tacrolimus (FK506)

Immunosuppressants that block T-cell cytokine production by inhibiting the phosphatase calcineurin and NFAT activation.

Mycophenolate Mofetil

A drug that blocks lymphocyte proliferation by inhibiting guanine nucleotide synthesis.

Rapamycin

An immunosuppressant that blocks lymphocyte proliferation by inhibiting $IL-2$ signaling.

Anti-CD52 (alemtuzumab)

A treatment that depletes lymphocytes by complement-mediated lysis.

Acute GVHD Timing

Typically occurs $3-30$ days after transfusion or within $30$ days for bone marrow transplants.

Chronic GVHD

Presence or persistence of GVHD beyond $100$ days post-transplant, which resembles collagen vascular disease.

Maculopapular Rash

A physical sign of GVHD appearing on the palms and soles following a bone marrow transplant.