What is HLA typing and why is it done?
• The HLA complex of genes on human chromosome 6 encodes proteins that are centrally involved in the actions of the immune system. In response to the diversity of infectious agents that have threatened human populations, the HLA genes have themselves diversified to the point at which most individuals have a different HLA type. These genetic differences individualize a person’s immune system. The combination of class I and class II antigens expressed by a person is called his/her HLA phenotype. The combination of class I and class II alleles is the HLA genotype. In most cases, the genotype reflects the phenotype. HLA typing identifies a person’s HLA type and, therefore, helps to characterize the immune function of that person. Different loci and different levels of resolution are required for different clinical applications. HLA typing is routinely used for matching donors and recipients in solid organ or hematopoietic stem cell transplantation (HSCT) / bone marrow transplantation, for
