****This web page was produced as an assignment for an undergraduate course at Davidson College.****
Immunological Vocabulary for Beginners
Allogeneic: A term describing non-self cells or tissues that differ from the host cells at the MHC locus or at other loci (Janeway et al., 2005).
Allograft: A tissue graft from an allogeneic donor. Allografts are rejected by the immune system unless the recipient of the graft undergoes immunosuppressant therapy (Janewayet al., 2005).
B cell: A B cell functions both as an antigen-presenting cell and as an effector cell in the humoral immune response. Once activated, it produces and releases antibodies (Janeway et al., 2005).
CD: The CD designation indicates that the molecule so named is a cell-surface molecule that is recognized by a group of monoclonal antibodies known as a cluster of differentiation (Janeway et al., 2005).
Graft-versus-host disease (GVHD): A major complication of allogeneic bone marrow transplantation. In this condition, mature donor T cells from the transplanted bone marrow recognize the recipient’s cells as non-self, leading to a severe inflammatory reaction characterized by rashes, diarrhea, and liver disease (Janeway et al., 2005).
Heterodimer: A functional protein composed of two different polypeptide subchains.
Homodimer: A functional protein composed of two identical polypeptide subchains.
Hypereosinophilia: A condition marked by an abnormally large number of eosinophils circulating in the bloodstream.
Immunoglobulin superfamily: Proteins belonging to this family are involved in antigen recognition and in cell-cell interaction and share structural features with immunoglobulin molecules. Each protein in this family contains one or more immunoglobulin or immunoglobulin-like domains (Janeway, et al., 2005).
Immunosuppressive drug: A compound that inhibits an adaptive immune response. Used mostly to prevent graft rejection and to treat severe autoimmune diseases (Janeway et al., 2005).
Immunotoxin: An anti-self antibody coupled to a toxin usually derived from a plant or an infectious agent. Much immunological research focuses on potential uses of immunotoxins as immunosuppressive drugs (Janeway et al., 2005).
Invariant: Unlike the TCR subchains, which express regions of variable amino acid sequences at their binding sites, all (non-mutated) CD3 subchains of a given type express the exact same amino acid sequence (Janeway et al., 2005).
ITAM: An immunoreceptor tyrosine-based activation motif (ITAM) consists of two tyrosine residues separated by between nine and 12 amino acid residues. In the classic ITAM sequence, either a leucine residue or an isoleucine residue occupies the fourth spot. ITAMs were initially identified in the cytoplasmic tails of CD3 molecules (Janeway et al., 2005).
Missense mutation: A mutation in which one nucleotide base is substituted for another.
Peripheral lymphoid organs: Organs in which immune responses are induced. Include the lymph nodes, the spleen, and mucosal-associated lymphoid tissues (Janeway et al., 2005).
Recombination signal sequence (RSS): A short segment of DNA flanking a gene segment to be rearranged during V(D)J recombination (Janeway et al., 2005).
Severe combined immunodeficiency: An immunodeficiency disease in which the immune system mounts neither T-cell mediated nor humoral responses. Fatal if untreated. Usually results from T cell deficiencies (Janeway et al., 2005).
Src-family tyrosine kinase: A receptor-associated protein tyrosine kinase with an SH2 domain that binds to ITAMs. These enzymes phosphorylate specific ITAMs on the cytoplasmic tails of receptor-associated accessory proteins to initiate a signaling transduction cascade (Janeway et al., 2005).
Thymocyte: A developing T cells found in the thymus. The CD3 complex plays a role in its development (Janeway et al., 2005).
Thymus: A central lymphoid organ in which T cells develop. Located behind the breastbone in the upper chest (Janeway et al., 2005).
T cell: A T cell is an effector cell that function in the cell-mediated immune response. There are three subsets of T cells (TH1, TH2, and cytotoxic) with different effector functions, but all three subsets express the CD3 complex (Janeway et al., 2005).
T-cell antigen receptor (TCR): The receptor on the T-cell surface that recognizes an antigen in the context of an MHC molecule. When TCR is associated with the other proteins in the TCR complex, the binding of a TCR to its peptide:MHC ligand triggers the signaling cascade that activates the T cell (Janeway et al., 2005).
V(D)J recombination: A process found exclusively in lymphocytes that allows for the recombination of gene segments into novel groupings. Accounts for the diversity of TCRs in normal individuals (Janeway et al., 2005).
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Literature Cited
Janeway, C. A., Travers, P., Walport, M., Sclomchik, M. J. 2005. Immunobiology: the immune system in health and disease, 6th ed. Garland Science Publishing, NY, pp. 753-777.
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Contact me. (Summerlee Walter) suwalter@davidson.edu)