human leukocyte antigen (HLA)

(noun)

The name of the major histocompatibility complex (MHC) in humans.

Examples of human leukocyte antigen (HLA) in the following topics:

  • MHC Polymorphism and Antigen Binding

    • MHC molecules display a molecular fraction called an epitope and mediate interactions of leukocytes with other leukocytes or body cells.
    • MHC molecules display a molecular fraction called an epitope and mediate interactions of leukocytes with other leukocytes or body cells.
    • Human MHC class I and II are also called human leukocyte antigen (HLA).
    • In humans, each HLA allele is named with a number.
    • The human leukocyte antigen (HLA) system is the name of the major histocompatibility complex (MHC) in humans.

  • Major Histocompatibility Complex Antigens (Self-Antigens)

    • MHC molecules mediate interactions of leukocytes with other leukocytes or body cells.
    • In humans, MHC is also called human leukocyte antigen (HLA), because MHC can often act as an antigen for human leukocytes.
    • MHC is also called human leukocyte antigen (HLA) and varies considerably among different members of the same species.
    • If the T and B cells of the body recognize the HLA of the graft as foreign, they will attack the organ graft.
    • If an organ donor has HLA similar to that of the recipient, the risk of organ rejection is reduced.

  • Antigen-Presenting Cells

    • Antigen presentation is a process where immune cells capture antigens and then enable their recognition by T-cells.
    • These antigens are different from those in bacteria ("non-self" antigens) or in virally-infected host cells ("missing-self").
    • Unlike B cells, T cells fail to recognize antigens in the absence of antigen presentation, with the important exception of the superantigens.
    • The T cell receptor is restricted to recognizing antigenic peptides only when bound to appropriate molecules of the major histocompatibility complex (MHC), also known in humans as Human leukocyte antigen (HLA).
    • In the upper pathway; foreign protein or antigen (1) is taken up by an antigen-presenting cell (2).

  • The Roles of Genetics and Gender in Autoimmune Disease

    • The misconception that an individual's immune system is totally incapable of recognizing self antigens is not new.
    • Therefore, any autoimmune response was perceived to be abnormal and postulated to be connected with human disease.
    • HLA DR3 is correlated strongly with Sjögren's syndrome, myasthenia gravis, SLE, and DM Type 1.
    • The most notable and consistent is the association between HLA B27 and ankylosing spondylitis.
    • HLA-DR is a MHC class II cell surface receptor encoded by the human leukocyte antigen complex on chromosome 6 region 6p21.31.

  • Cytotoxic Autoimmune Reactions

    • The misconception that an individual's immune system is totally incapable of recognizing self antigens is not new.
    • Thus, any autoimmune response was perceived to be abnormal and postulated to be connected with human disease.
    • HLA DR3 is correlated strongly with Sjögren's syndrome, myasthenia gravis, SLE, and DM Type 1.
    • The most notable and consistent is the association between HLA B27 and ankylosing spondylitis.
    • HLA-DR is a MHC class II cell surface receptor encoded by the human leukocyte antigen complex on chromosome 6 region 6p21.31.

  • Cell-Mediated Autoimmune Reactions

    • A feature of human autoimmune disease is that it is largely restricted to a small group of antigens, several of which have known signaling roles in the immune response (for example DNA, C1q, IgGFc, Ro, Con.
    • HLA-DQ (DQ) is a cell surface receptor type protein found on antigen presenting cells.
    • The α and β chains are encoded by HLA-DQA1 and HLA-DQB1, respectively.
    • Two autoimmune diseases in which HLA-DQ is involved are celiac disease and diabetes mellitus type 1.
    • HLA-DQ (DQ) is a cell surface receptor type protein found on antigen presenting cells (APC).

  • Cells and Organs of the Immune System

    • In humans, red blood cells are produced in the heads of long bones.
    • The innate leukocytes include the phagocytes, mast cells, eosinophils, basophils, and natural killer cells.
    • Natural killer cells are leukocytes that attack and destroy tumor cells, or cells that have been infected by viruses.
    • The cells of the adaptive immune system are special types of leukocytes, called lymphocytes .
    • In contrast, the B cell antigen-specific receptor is an antibody molecule on the B cell surface, which recognizes whole pathogens without any need for antigen processing.

  • Pathogen Recognition

    • At least 40 types of cytokines exist in humans that differ in terms of the cell type that produces them, the cell type that responds to them, and the changes they produce.
    • A neutrophil is also a phagocytic leukocyte that engulfs and digests pathogens .
    • An eosinophil is a leukocyte that works with other eosinophils to surround a parasite.
    • Eosinophils and basophils produce additional inflammatory mediators to recruit more leukocytes.
    • A hypersensitive immune response to harmless antigens, such as in pollen, often involves the release of histamine by basophils and mast cells; this is why many anti-allergy medications are anti-histamines.

  • Development of the Dual Lymphocyte System

    • The cells of the adaptive immune system are a type of leukocyte, called a lymphocyte.
    • The human body has about 2 trillion lymphocytes, constituting 20-40% of white blood cells (WBCs); their total mass is about the same as the brain or liver.
    • B and T cells) differentiate further after exposure to an antigen; they form effector and memory lymphocytes.
    • Effector lymphocytes function to eliminate the antigen, either by releasing antibodies (in the case of B cells), cytotoxic granules (cytotoxic T cells) or by signaling to other cells of the immune system (helper T cells).
    • Memory cells remain in the peripheral tissues and circulation for an extended time ready to respond to the same antigen upon future exposure.

  • Types of Cytokines Participating in Immune Response

    • They provide the signaling pathways that orchestrate the complex immune responses of the human body.
    • Interleukins are a class of cytokines primarily expressed by leukocytes.
    • Some of the more important ones include inflammatory mediators such as IL-1, IL-4, and IL-6, the potent anti-inflammatory IL-10, and other interleukins involved with T and B cell signaling following antigen presentation.
    • Leukocytes travel along chemotactic gradients that guide them to sites of injury, infection, or inflammation.
    • This category also includes cytokines that are only involved in leukocyte migration, such as CCL2 which causes monocyte chemotaxis and stimulates its differentiation into macrophages inside of tissues.