tissue typing

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Tissue typing

A procedure involving a test or a series of tests to determine the compatibility of tissues from a prospective donor and a recipient prior to transplantation. The immunological response of a recipient to a transplant from a donor is directed against many cell-surface histocompatibility antigens controlled by genes at many different loci. However, one of these loci, the major histocompatibility complex (MHC), controls antigens that evoke the strongest immunological response. The human MHC is known as the HLA system, which stands for the first (A) human leukocyte blood group system discovered. See Cellular immunology, Histocompatibility

The success of transplantation is greatly dependent on the degree of histocompatibility (identity) between the donor and recipient, which is determined by the HLA complex. When the donor and recipient have a low degree of histocompatibility, the organ is said to be mismatched, and the recipient mounts an immune response against the donor antigen. By laboratory testing, the degree of antigenic similarity between the donor and the recipient and the degree of preexisting recipient sensitization to donor antigens (and therefore preformed antibodies) can be determined. This is known as cross-matching.

Phenotyping of HLA-A, -B, and -C (ABC typing) of an individual is determined by reacting that individual's lymphocytes with a large panel of antisera directed against specific HLA antigens. The procedure is known as complement-mediated cytotoxicity assay. The person's lymphocytes are incubated with the different antisera and complement is added. Killing of the cells being tested indicates that they express the HLA antigens recognized by the particular antiserum being used. Killing of potential donor lymphocytes in the complement-mediated cytotoxicity assay is a contraindication to transplantation of tissue from that donor. See Complement, Hypersensitivity, Immunoassay

In addition to its important role in organ transplantation, determination of the HLA phenotype is useful in paternity testing, forensic medicine, and the investigation of HLA-disease associations. See Transplantation biology

tissue typing

[′tish·ü ‚tīp·iŋ]
A procedure involving a test or a series of tests to determine the compatibility of tissues from a prospective donor and a recipient prior to transplantation.
References in periodicals archive ?
Michael Cecka, MD, a UCLA professor of pathology and laboratory medicine, observed: "Not only has tissue typing been key to the success of bone marrow transplants and prolonged graft survival for patients fortunate to receive a well-matched kidney transplant, but the cross-match test he developed in the 1960s is still used today for all kidney transplant patients and select candidates for heart, lungs, pancreata, bowels and sometimes liver transplantation to avoid catastrophic rejections that are mediated by antibodies against the donor's human leukocyte antigens.
In arriving at its new policy, the HFEA re-examined the risks associated with IVF and embryo biopsy--interventions that are required for PGD--and concluded that these risks are acceptable regardless of whether PDG tissue typing is done in conjunction with disease testing or in isolation from it.
The HFEA said it would look at developments in science and law and the ethical debate surrounding pre-implantation tissue typing as part of its review.
HLA testing, also referred to as tissue typing, is a key component in determining the compatibility between potential donors and recipients prior to transplantation to maximise the chances of graft survival and minimise serious immunologic transplant complications.
He first used standard tissue typing methods to study blood samples from a series of 61 Norwegian MS patients, and found that 59 of them were positive for DR2, 4 or 6.
Major revisions have been made to the section on primary immunodeficiencies to demonstrate the advances in understanding genetics, tissue typing, and therapeutics.
Ms Quintavalle and Core believe that there can now be no more issuing of tissue typing licences pending the hearing in the Court of Appeal.
Of the 4 million people nationwide who have given blood for tissue typing in the National Bone Marrow Registry, only 340,000 are African- American, and only 355,000 are Latino, according to the American Red Cross.
HBOS Foundation have donated pounds 5,000 to cover the cost of tissue typing 70 people from the ECHO clinic.
Mr Justice Maurice Kay ruled the HFEA overstepped its powers in licensing embryo selection by tissue typing and had not understood the 1990 Human Fertilisation and Embryology Act.
Through grants and fundraising by the Puget Sound Blood Center, the $75 tissue typing cost has been reduced to $25.

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