What is the Origin of HLA Type?

The term originates from the study of tissue compatibility for transplantation, where 'Human Leukocyte Antigen' refers to the antigens first identified on white blood cells (leukocytes) that are responsible for graft rejection. The MHC region, where the HLA genes reside, is one of the most gene-dense and variable regions of the human genome. Specific HLA alleles, such as certain DR and DQ haplotypes, were later strongly correlated with increased risk for various autoimmune diseases.

What is the Mechanism of HLA Type?

HLA molecules function by binding to small peptide fragments, presenting them to T-lymphocytes to initiate an immune response. In autoimmune endocrine disorders like Type 1 Diabetes, Graves' disease, or Hashimoto's thyroiditis, a particular HLA type may possess a structural conformation that preferentially binds and presents a 'self-peptide' (e.g., a fragment of a thyroid or pancreatic cell protein) to T-cells. This misidentification breaks immune tolerance, causing the T-cells to attack and destroy the hormone-producing cells in the endocrine gland.

HLA Type

Meaning

HLA Type refers to the specific combination of Human Leukocyte Antigens, which are proteins encoded by the Major Histocompatibility Complex (MHC) genes located on chromosome 6. These cell-surface proteins are crucial for immune system function, enabling immune cells to distinguish between the body’s own cells and foreign invaders like pathogens. A person’s HLA type is highly polymorphic and is a primary determinant of genetic susceptibility to autoimmune endocrine disorders.