
Transplantation is a procedure wherein diseased or injured cells, tissues, or organs are replaced with healthy cells, tissues, or organs to restore normal functioning of the body. Donor and recipient cells, tissues, and organs should match or be compatible, or can lead to transplant rejection. The surface of the transplanted organs contains antigens, which the recipient's immune system may not adapt to. This can lead to rejection of an organ. Hence, serological and human leukocyte antigen (HLAs) tests are conducted to help identify the antigens and help in successful organ transplantation. With HLA testing, immunosuppressive drugs are provided to minimize graft rejection. In humans, major histocompatibility complex controlled by the genes located on chromosome 6 is responsible for ensuring compatibility between donors and recipients.