Transplant Immunology Lab

The Transplant Immunology Lab at Walter Reed National Military Medical Center (WRNMMC) provides histocompatibility testing for solid organ transplantation and transfusion support (e.g. patients requiring HLA-compatible platelet transfusions). There are typically three components of HLA testing used to determine compatibility in solid organ transplantation:

1. HLA typing of donor and recipients. HLA antigens represent major barriers to organ and tissue transplantation between individuals. HLA typing identifies the unique constellation of HLA antigens for an individual. The Transplant Immunology Lab uses serological and newer molecular diagnostic techniques for HLA typing, as well as DNA typing, which provides more accurate and reliable results, especially in resolving allele-level differences in HLA genes that cannot be detected by serology.
    
2. HLA antibody screening or recipients. Patients who have become sensitized to allogeneic HLA antigens through pregnancies, blood transfusions, failed transplants, or other means represent a challenge when requiring a transplant or platelet transfusion. Preformed anti-HLA antibodies are associated with hyperacute rejection of grafts, failure of platelet transfusions, and accelerated loss of solid organ transplants. These antibodies can be identified on solid phase assays on luminex platform. This assay is used to monitor patients for the presence or absence of anti-HLA class I and class II antibodies. HLA antibody testing may be periodically performed and updated to determine if the person waiting for a matching organ to become available has developed additional HLA antibodies. HLA antibody assessment can also be used post transplant to determine if the recipient has developed new or increased levels of antibodies to the donor.
    
3. Crossmatching. Crossmatch tests are used primarily for transplant candidates to assess the suitability of a potential donor. The lab performs T and B cell crossmatching by complement-dependent lymphocytotoxicity (CDC). Serum from the intended recipient is mixed with white blood cells (T and B lymphocytes) from the donor. Any reaction detected (a positive result) would indicate likely incompatibility between the two. The crossmatch result is always interpreted along with known information regarding the recipient’s antibodiy specificities and the donor HLA typing.

The Transplant Immunology Laboratory can provide high resolution HLA testing for vaccine development, drug therapy, clinical trials, and HLA disease associations. We are developing the ability to provide crossmatch testing by flow cytometry. Positive CDC crossmatching identifies the most important IgG antibodies responsible for hyperacute rejection of grafts. Positive crossmatches detected only by flow cytometry carry a risk of accelerated rejection and damage to the graft. Both are interpreted with the patient’s past sensitization history.