Test Details: Human leukocyte antigens (HLA) are a system of glycoproteins that have a functional role in the presentation of peptides to the immune system. However, as a highly polymorphic system, HLA molecules can become the targets of antibody responses in people during pregnancy, transfusion of blood products, or organ transplant rejection. Generally, alloimmunization leads to the production of HLA antibodies in approximately 33% of exposed individuals. The presence or absence of these HLA-specific antibodies has negative effect on survival of transplant allografts. T and B cell Lymphocyte crossmatching helps to determine whether the intended recipient has cell mediated and antibody mediated reaction against the antigens present on the prospective donor lymphocytes. The crossmatch results need to be interpreted considering the recipient antibody status and the donor HLA typing.