Tissue compatibility In pretransplantation screening, recipients and donors are tested for Human leukocyte antigens (HLAs; also called the major histocompatibility complex [MHC]) ABO antigens Recipients are tested for Presensitization to donor antigens HLA tissue typing is most important for the following: Kidney transplantation The most common types of hematopoietic stem cell transplantation Transplantation of the following typically occurs urgently, often before HLA tissue typing can be completed, so the role of matching for these organs is less well-established: Heart Liver Pancreas Lung HLA tissue typing of peripheral blood or lymph node lymphocytes is used to match the most important known determinants of histocompatibility in the donor and recipient.