An autoinﬂammatory disease characterized by recurrent, periodic episodes of inﬂammation and fever caused by mutations in gene that encodes TNF receptor I. The defective TNFR-I proteins fold abnormally and accumulate in cells in such a way that they spontaneously activate production of TNF-α. See also familial Mediterranean fever.
TNF receptors Family of cytokine receptors which includes some that lead to apoptosis of the cell on which they are expressed (for example Fas and TNFR-I), whereas others lead to activation.
tocilizumab Humanized anti-IL-6 receptor antibody used in treating rheumatoid arthritis.
tofacitinib An inhibitor of JAK3 and JAK1 used to treat rheumatoid arthritis and under investigation in other inﬂammatory disorders.
tolerance The failure to respond to an antigen. Tolerance to self antigens is an essential feature of the immune system; when tolerance is lost, the immune system can destroy self tissues, as happens in autoimmune disease.
tolerant   Describes the state of immunological tolerance, in which the individual does not respond to a particular antigen.
tolerogenic Describes an antigen or type of antigen exposure that induces tolerance.
Toll Receptor protein in Drosophila that activates the transcription factor NFκB, leading to the production of antimicrobial peptides.
Toll-like receptors (TLRs)   Innate receptors on macrophages, dendritic cells, and some other cells, that recognize pathogens and their products, such as bacterial lipopolysaccharide. Recognition stimulates the receptor-bearing cells to produce cytokines that help initiate immune responses.
tonsils See lingual tonsils, palatine tonsils.
toxic shock syndrome A systemic toxic reaction caused by the massive production of cytokines by CD4 T cells activated by the bacterial superantigen toxic shock syndrome toxin-1 (TSST-1), which is secreted by Staphylococcus aureus.
toxic shock syndrome toxin-1 (TSST-1) See toxic shock syndrome.
toxoids Inactivated toxins that are no longer toxic but retain their immunogenicity so that they can be used for immunization.
TRAF3 An E3 ligase that produces a K63 polyubiquitin signaling scaffold in TLR-3 signaling to induce type I interferon gene expression.
TRAF6 (tumor necrosis factor receptor-associated factor 6) An E3 ligase that produces a K63 polyubiquitin signaling scaffold in TLR-4 signaling to activate the NFκB pathway.
A member of the TNF cytokine family expressed on the cell surface of some cells, such as NK cells, that induces cell death in target cells by ligation of the 'death' receptors DR4 and DR5.
TRAM An adaptor protein that pairs with TRIF in signaling by TLR-4.
transcytosis The active transport of molecules, such as secreted IgA, through epithelial cells from one face to the other.
Transib A superfamily of transposable elements identified computationally and proposed to date back more than 500 million years and to have given rise to transposons in diverse species.
transitional immunity Referring to the recognition by some adaptive immune system (e.g., MAIT, γ:δT cells) of non-peptide ligands expressed as a consequence of infection, such as various MHC class Ib molecules.
transitional stages Defined stages in the development of immature B cells into mature B cells in the spleen, after which the B cell expresses B-cell co-receptor component CD21.
transporters associated with antigen processing-1 and -2 (TAP1 and TAP2) See TAP1, TAP2.
transposase An enzyme capable of cutting DNA and allowing integration and excision of transposable genetic elements into or from the genome of a host.