immunoglobulin new antigen receptor (IgNAR) A form of heavy-chainonly Ig molecule made by shark species.
immunoglobulin repertoire The variety of antigen-specific immunoglobulins (antibodies and B-cell receptors) present in an individual. Also known as the antibody repertoire.
immunoglobulin superfamily Large family of proteins with at least one Ig or Ig-like domain, many of which are involved in antigen recognition and cell– cell interaction in the immune system and other biological systems.
immunological ignorance A form of self-tolerance in which reactive lymphocytes and their target antigen are both detectable within an individual, yet no autoimmune attack occurs.
immunological memory The ability of the immune system to respond more rapidly and more effectively on a second encounter with an antigen. Immunological memory is specific for a particular antigen and is long-lived.
immunological synapse The highly organized interface that develops between a T cell and the target cell it is in contact with, formed by T-cell receptors binding to antigen and cell-adhesion molecules binding to their counterparts on the two cells. Also known as the supramolecular adhesion complex.
immunological tolerance See tolerance.
immunologically privileged sites   Certain sites in the body, such as the brain, that do not mount an immune response against tissue allografts. Immunological privilege can be due both to physical barriers to cell and antigen migration and to the presence of immunosuppressive cytokines.
immunology The study of all aspects of host defense against infection and also of the adverse consequences of immune responses.
immunomodulatory therapy Treatments that seek to modify an immune response in a beneficial way, for example to reduce or prevent an autoimmune or allergic response.
immunophilins See cyclophilins, FK-binding proteins.
immunoproteasome A form of proteasome found in cells exposed to interferons. It contains three subunits that are different from the normal proteasome.
immunoreceptor tyrosine-based activation motif (ITAM) Sequence motifs in the signaling chains of receptors, such as antigen receptors on lymphocytes, that are the site of tyrosine phosphorylation after receptor activation, leading to recruitment of other signaling proteins.
immunoreceptor tyrosine-based inhibition motif (ITIM) Sequence motifs in the signaling chains of inhibitory receptors that are sites of tyrosine phosphorylation, leading to inhibitory signaling, such as through recruitment of phosphatases that remove phosphate groups added by tyrosine kinases.
immunoreceptor tyrosine-based switch motif (ITSM) A sequence motif present in the cytoplasmic tails of some inhibitor receptors.
immunotoxin Antibodies that are chemically coupled to toxic proteins usually derived from plants or microbes. The antibody targets the toxin moiety to the required cells.
indirect allorecognition Recognition of a grafted tissue that involves the uptake of allogeneic proteins by the recipient’s antigen-presenting cells and their presentation to T cells by self MHC molecules.
indoleamine 2,3-dioxygenase (IDO) Enzyme expressed by immune cells and some tumors that catabolizes tryptophan into kynurenine metabolites that can have immunosuppressive functions.
induced pluripotent stem cells (iPS cells) Pluripotent stem cells that are derived from adult somatic cells by the introduction of a cocktail of transcription factors.
infectious mononucleosis The common form of infection with the Epstein–Barr virus. It consists of fever, malaise, and swollen lymph nodes. Also called glandular fever.
inflammasome A pro-inﬂammatory protein complex that is formed after stimulation of the intracellular NOD-like receptors. Production of an active caspase in the complex processes cytokine proproteins into active cytokines.