Clinical Tissue Typing/Transplant
The Clinical Tissue Typing/Transplant Laboratory provides state-of-the-art histocompatibility and immunogenetics testing for solid organ and stem cell transplantation, disease diagnosis and transfusion support. The laboratory is accredited by ASHI and CAP and has a comprehensive quality assurance program.
HLA antigens are integral cell membrane glycoproteins, which play a key role in immunity. These molecules represent major barriers to transplantation and have also been implicated in many disease processes. Two distinct classes of structurally similar HLA antigens have been well characterized and differ in their tissue distribution – class I HLA-A, -B, -C antigens are expressed ubiquitously on nucleated cells, whereas the class II HLA-DR, -DQ, -DP antigens are normally expressed on B cells, monocytes, macrophage, dendritic cells and on activated T cells.
HLA typing identifies the unique constellation of HLA antigens for an individual. Tests of HLA-class I (A, B, C) and class II (DR, DQ, DP) is performed by DNA-based molecular diagnostic techniques. HLA typing using these newer DNA technologies provides more robust, accurate testing that is reliable in resolving allele-level differences in HLA genes that cannot be detected by serology. Several approaches to HLA typing are used, offering a range of typing resolution levels from low (antigen-level) to high (allele-level). Tests used to identify HLA types rely on amplification of limited stretches of genomic DNA within the HLA genes. The genetic polymorphisms associated with the different HLA alleles are identified through hybridization with specific amplification primers (SSP) or probes (SSO). Our laboratory provides HLA typing by both these methodologies.
Natural killer (NK) cells are the integral component of innate immunity. They kill infected cells, tumors and stressed cells without prior sensitization. Further, they secrete inflammatory cytokines which drive the antigen specific adaptive immunity. The inhibitory KIRs recognize determinants expressed on the surface of abnormal cells and subvert these unhealthy cells. Genes encoding KIRs and HLA ligands belong to polymorphic gene families located on different chromosomes. Since the integration of signals transduced from inhibitory and activating KIR receptors help to balance the NK cell response between tolerance of healthy cells and killing of unhealthy cells, the combinations of KIR and HLA class I molecules play an important role in human immunity and disease. The KIR genotyping test identifies the presence and absence of 15 distinct KIR genes. This test is offered by our laboratory by DNA SSP methodology and helps donor selection for bone marrow transplantation.
PRA and antibody identification testing
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 acute rejection of kidney grafts, failure of platelet transfusions and accelerated and chronic loss of solid organ transplants. Preformed anti-HLA antibodies may cause transfusion-related acute lung injury (TRALI) in some recipients. Sensitization is reported as the percent Panel Reactive Antibody (PRA). The PRA also gives an estimate of the likelihood of finding a suitable donor. Patients who have autoimmune diseases, are on particular medications, or have infections may develop false positive reactions that are not caused by anti-HLA antibodies. Results are reported as the percent PRA and the anti-HLA specificities that were identified. Our laboratory performs this test on luminex platform that uses single recombinant HLA class I and class II antigens coupled to micro particles.
Flow cytometry cross match
This test is used primarily for solid organ transplant candidates to assess the suitability of a potential donor. Positive cross matches detected by flow cytometry suggest the presence of preformed anti-donor HLA antibodies and carry a risk of accelerated rejection and damage to the graft. These sensitive cross matches are interpreted in terms of the patient’s sensitization history and the quality of the donor organ. Our laboratory reports flow cytometry results as positive or negative based upon the median channel shift caused by the binding of a specific antibody.
Virtual Cross match
Cross match results can now be accurately predicted when the patient’s antibody specificities have been identified using recombinant single HLA antigen bead technologies and the potential donor HLA type is known. Our laboratory provides virtual cross matches for potential recipient donor pairs.
Director and Technical Supervisor
Sujata Gaitonde, MD
Carol Wasik, MT(ASCP), CHS(ABHI) – Manager
Wuhua Sun, MS
Kristin Dastych, BS
Juan Chen, MS
Hours of Operation: Monday through Friday, 8:30 am to 5:00 pm
Address: Histocompatibility (HLA) Laboratory
808 South Wood Street, Room 266
Chicago, IL 60612