Immunological synapse
Encyclopedia
In immunology
Immunology
Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. It deals with the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders ; the...

, an immunological synapse (or immune synapse) is the interface between an antigen-presenting cell
Antigen-presenting cell
An antigen-presenting cell or accessory cell is a cell that displays foreign antigen complexes with major histocompatibility complex on their surfaces. T-cells may recognize these complexes using their T-cell receptors...

 and a lymphocyte
Lymphocyte
A lymphocyte is a type of white blood cell in the vertebrate immune system.Under the microscope, lymphocytes can be divided into large lymphocytes and small lymphocytes. Large granular lymphocytes include natural killer cells...

. It was first discovered by Abraham Kupfer
Abraham Kupfer
Abraham Kupfer, Ph.D., is a professor of cell biology, and the co-director of immunobiology at the Johns Hopkins University School of Medicine. Abraham discovered the immunological synapse at the National Jewish Medical and Research Center in Denver...

 at the National Jewish Medical and Research Center
National Jewish Medical and Research Center
National Jewish Health is a research institute located in Denver, Colorado specializing in respiratory, immune and allergic research and treatment. It was founded in 1899 to treat tuberculosis, and is today considered one of the world's best medical research and treatment centers...

 in Denver and the term was coined by Michael Dustin at NYU who studied it in further detail. Daniel Davis and Jack Strominger showed structured immune synapses for a different lymphocyte, the Natural Killer cell
Natural killer cell
Natural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses...

, and published this around the same time . Abraham Kupfer first presented his findings during one of the Keystone symposia in 1995, when he showed three dimensional images of immune cells interacting with one another. Key molecules in the synapse are the T cell receptor
T cell receptor
The T cell receptor or TCR is a molecule found on the surface of T lymphocytes that is responsible for recognizing antigens bound to major histocompatibility complex molecules...

 and its counterpart the major histocompatibility complex (MHC
MHC
-Biology:*Myosin heavy chain - part of the motor protein myosin's quaternary protein structure*Major histocompatibility complex - a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions-Colleges:...

). Also important are LFA-1
LFA-1
Lymphocyte function-associated antigen 1, also known as LFA-1 is found on all T-cells and also on B-cells, macrophages and neutrophils and is involved in recruitment to the site of infection. It binds to ICAM-1 on antigen-presenting cells and functions as an adhesion molecule. LFA-1 is the first...

, ICAM-1
ICAM-1
ICAM-1 also known as CD54 is a protein that in humans is encoded by the ICAM1 gene. This gene encodes a cell surface glycoprotein which is typically expressed on endothelial cells and cells of the immune system...

, CD28
CD28
CD28 is one of the molecules expressed on T cells that provide co-stimulatory signals, which are required for T cell activation. CD28 is the receptor for CD80 and CD86 . When activated by Toll-like receptor ligands, the CD80 expression is upregulated in antigen presenting cells...

, and CD80
CD80
Cluster of Differentiation 80 is a protein found on activated B cells and monocytes that provides a costimulatory signal necessary for T cell activation and survival...

/CD86
CD86
Cluster of Differentiation 86 is a protein expressed on antigen-presenting cells that provides costimulatory signals necessary for T cell activation and survival...

.

The immune synapse is also known as the supramolecular activation cluster or SMAC. This structure is composed of concentric rings each containing a peculiar mix of molecules:
  • c-SMAC (central-SMAC) composed of θ isoform
    PRKCQ
    Protein kinase C theta type is an enzyme that in humans is encoded by the PRKCQ gene.-Interactions:PRKCQ has been shown to interact with FYN, GLRX3, AKT1 and VAV1.PRKCQ has been shown to phosphorylate CARD11 as part of the NF-κB signaling pathway....

     of protein kinase C
    Protein kinase C
    Protein kinase C also known as PKC is a family of enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins. PKC enzymes in turn are activated by signals such as increases in...

    , CD2
    CD2
    CD2 is a cell adhesion molecule found on the surface of T cells and natural killer cells.It has also been called T-cell surface antigen T11/Leu-5, LFA-2, LFA-3 receptor, erythrocyte receptor and rosette receptor....

    , CD4
    CD4
    CD4 is a glycoprotein expressed on the surface of T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 before being named CD4 in 1984...

    , CD8
    CD8
    CD8 is a transmembrane glycoprotein that serves as a co-receptor for the T cell receptor . Like the TCR, CD8 binds to a major histocompatibility complex molecule, but is specific for the class I MHC protein. There are two isoforms of the protein, alpha and beta, each encoded by a different gene...

    , CD28
    CD28
    CD28 is one of the molecules expressed on T cells that provide co-stimulatory signals, which are required for T cell activation. CD28 is the receptor for CD80 and CD86 . When activated by Toll-like receptor ligands, the CD80 expression is upregulated in antigen presenting cells...

    , Lck
    Lck
    Lck is a protein that is found inside specialized cells of the immune system called lymphocytes. Lck is a tyrosine kinase, which phosphorylates tyrosine residues of certain proteins involved in the intracellular signaling pathways of these lymphocytes...

    , and Fyn
    FYN
    Proto-oncogene tyrosine-protein kinase Fyn is an enzyme that in humans is encoded by the FYN gene.This gene is a member of the protein-tyrosine kinase oncogene family. It encodes a membrane-associated tyrosine kinase that has been implicated in the control of cell growth...

    .
  • p-SMAC (peripheral-SMAC) in the lymphocyte function-associated antigen-1 (LFA-1) and the cytoskeletal protein talin
    Talin protein
    Talin is a high-molecular-weight cytoskeletal protein concentrated at regions of cell–substratum contact and, in lymphocytes, at cell–cell contacts. Discovered in 1983 by Keith Burridge and colleagues, talin is a ubiquitous cytosolic protein that is found in high concentrations in focal adhesions...

     are clustered.
  • d-SMAC (distal-SMAC) enriched in CD43
    CD43
    Leukosialin also known as sialophorin or CD43 is a transmembrane cell surface protein that in humans is encoded by the SPN gene.- Function :...

     and CD45 molecules.

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