RT Book, Section A1 Levinson, Warren A1 Chin-Hong, Peter A1 Joyce, Elizabeth A. A1 Nussbaum, Jesse A1 Schwartz, Brian SR Print(0) ID 1190864828 T1 Major Histocompatibility Complex & Transplantation T2 Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 17e YR 2022 FD 2022 PB McGraw-Hill Education PP New York, NY SN 9781264267088 LK accessmedicine.mhmedical.com/content.aspx?aid=1190864828 RD 2024/03/28 AB In transplantation, an organ or tissue from one person is “grafted” to another person. A major barrier to the success of these life-saving procedures is the immune system, which attacks any cells it sees as foreign. Graft survival is largely determined by the donor’s and recipient’s major histocompatibility complex (MHC) proteins, which present antigens to T cells. In humans, these proteins are encoded by the human leukocyte antigen (HLA) genes. (Note that we will use MHC and HLA interchangeably.) Three of these genes (HLA-A, HLA-B, and HLA-C) code for the class I MHC proteins. Several HLA-D loci determine the class II MHC proteins (i.e., DP, DQ, and DR) (Figure 62–1). The features of class I and class II MHC proteins are compared in Table 62–1. If the HLA proteins on the donor’s cells differ from those on the recipient’s cells, then an immune response occurs in the recipient.