Adaptive immunity: Acquired immunity and response triggered by specificity of antigen recognition

Adjuvant: Strong stimulants of the immune system, e.g. bacterial lipopolysaccharide

Anergy: Inactivation of lymphocytes leading to an absence of an immune response and producing immune tolerance

Antibody: Essential in immunity, molecule produced by a mature B cell that recognizes and binds specifically to an antigen also called immunoglobulin

Antibody-dependent cell-mediated cytotoxicity: Antibody binds to a target cell, marking it for destruction. Several other cells participate and cause the cell to lyse

Antigen: A substance that is recognized by the immune system and triggers an immune reaction

Antigen presentation: Process by which an antigen is presented to a T cell in a form in which it can be recognized

Antigen receptor: A protein that recognizes and binds to an antigen, e.g. T cell receptor is an antigen-binding receptor found on T cell surface

Antigen-presenting cells: Cells which process antigens and have special molecules (MHC) that bind the processed antigens and display them on the cell surface for T cells to recognize

Antimicrobial proteins: Found inside cells, in the blood and in milk, involved in response against bacteria, e.g. defensins

Apoptosis: Programmed cell death

Autoantigen: See self antigen

Autoimmunity: Condition in which the immune system reacts against the body's own tissue

B cells: Named for bone marrow, these lymphocytes differentiate into antibody-producing cells

B lymphocytes:See B cells

Carcinoma: Type of malignant cancer of epithelial cells

CD antigens: "Cluster of differentiation" surface markers on leukocyte cell surface. Refers to groups of monoclonal antibodies that show similar reactivity with certain subpopulations of antigens of a particular lineage or differentiation stage. Range in number from CD1 antigen to CD226, e.g. Fas antigen is a CD95 antigen

Cell adhesion molecules: Cell surface glycoproteins responsible for binding of one cell to another

Cell-mediated immunity: T cells secrete lymphokines or directly attack the pathogens or tumor cells to defend the body

Cell transformation: Process by which a normal, non-dividing cell becomes cancerous, escaping normal restrictions which control cell division

Chimeric molecule: Molecule made up of two separate proteins

Costimulatory molecules: The primary molecules involved in antigen presentation are MHC-antigen and TCR. However other cell surface molecules are also required for antigen presentation, e.g. CD28, CD80, and CD86; these are called Costimulatory molecules

Cytokines: Proteins involved in signaling between immune cells, across short distances

Cytotoxic T cell: T cell with CD8 antigen on cell surface, recognizes HLA class 1 antigens presented on cell and kills the cell. Also called CD8 cells and killer cells

Dendritic Cells (DCs): Antigen-presenting cells with a branched structure

DNA vaccine: Gene is introduced in an expression vector that allows transcription and translation into the protein

Effector cells: T cells which carry out immune functions, namely, helper T cells and cytotoxic T cells

Eosinophils: White blood cells with a lobed nucleus most active at sites of inflammation, named for ability to stain with the dye eosin

Genomics: Study of the DNA sequences of an organism

Graft-versus-host reaction: An immune reaction in which the donor tissue sets up an immune response against the host into which it is transplanted

Helper T cells (Th cells): T cells that are essential for many immune responses. CTL and B cells functioning in cooperation with T helper cells have the CD4 antigen

Hematopoiesis: Development of blood cells including immune cells in the bone marrow

Humoral Immunity: Antibodies secreted by mature B cells involved in defending the body against pathogens and tumors

Immune surveillance: Detection of tumor growth by the immune system

Immunogenicity: Ability to trigger an immune response, e.g. highly immunogenic substance can trigger a strong immune response

Immunological memory: The repeated encounter with an antigen leads to a stronger immune response

Immunosuppression: Certain drugs and cytokines can lower the immune response either of specific cells or produce an overall effect of reducing the immune response

Immunotherapy: Treatment of a disease by manipulation of the host's immune system

Innate immunity: Immunity one is born with; this type of immune response is not associated with specific antigens

Interferon-gamma: Type of cytokine, involved in anti-virus immunity

Interleukins: A group of about 30 related cytokines that have specific effects on immune cells named Interleukin-1(or IL-1), etc.

Killer activating receptors: Proteins present on NK cells, when activated cause NK cells to kill a target cell

Killer inhibitory receptors: Proteins present on NK cells, when activated prevent NK cells from killing a target cell

Leukemia: Progressive, malignant cancer of blood-forming tissue

Lymphoma: Cancer of lymphoid tissue

Lysis of cells: Also called cytolysis, bursting of cells (verb: lyse)

Macrophages: Phagocytic cells derived from monocytes found in many different tissues

Major histocompatibility complex (MHC): Originally recognized as antigens responsible for graft rejection in incompatible hosts after transplantation. These are molecules that bind with processed antigens and are displayed on the surface of cells. MHC class I molecules are displayed on non-immune cells and MHC class II on antigen-presenting cells

Mast cells: Cells found in gastrointestinal tract and skin. They contain histamines and play a vital role in inflammation and allergy

Melanoma: Malignant form of skin cancer

Memory cells: T or B cells involved in immune response against a repeated encounter with an antigen

Metastasis: Spreading of cancer cells from the primary site to distant region(s) in the body

MHC-antigen complex: Major histocompatibility complex bound to an antigen displayed on the cell surface

Monoclonal antibodies: Antibodies that recognize only one antigen and bind it specifically by recognizing part of its structure

Monocytes: Large white blood cells capable of phagocytosis that are produced in the bone marrow and develop into macrophages

Natural killer cells (NK cells): Cells of the innate immune system involved in attacking tumor cells without recognizing specific antigen

Natural killer T cells: Different from natural killer cells. Involved in destroying metastatic cancer cells; these cells share characteristics of T cells and NK cells

Neutrophils: White blood cells that have a multi-lobed nucleus and are active against bacteria, stain with neutral dyes

Pattern-recognition receptors: Proteins found in many species that recognize common bacterial cell surface antigens; the most common ones are the toll-like receptors found on macrophage cell surface

Phagocyte: Cell that engulfs another cell, also called phagocytic cell

Phagocytosis: Engulfing of a cell by another cell, the latter is called a phagocyte

Plasma cells: Antibody producing cells derived from B cells

Regulatory T cells: Limit the activity of other T cells to prevent an uncontrolled immune reaction leading to autoimmunity

Self antigen: Normal substance in the body that can trigger an immune response leading to autoimmunity

Self tolerance: Absence of immune reaction against cells or tissue of one's own body

Suppressor T cells: See Regulatory T cells

T cell activation: Process by which antigen presentation triggers changes within the T cells, eventually leading to activation of genes involved in cell differentiation and cell division

T cell receptor: Cell surface molecule on T cells which recognizes and binds to MHC-antigen complex on body cells and antigen-presenting cells

T cells: Immune cells responsible for cell-mediated immunity. Named for Thymus (the organ in which they mature). There are different types of T cells: cytotoxic, helper, regulatory, suppressor and memory

T lymphocytes: see T cells

Thymus: Lymphoid organ required for immune development

Tolerance (immunological): When no immune response is mounted against an antigen. Self cells and tumors are tolerated because they possess self antigens

Tumor antigens: Molecules displayed on the surface of tumor cells and recognized by immune cells. Tumor-specific antigens (TSA) are specific to tumors and not found in normal tissue, while tumor-associated antigens (TAA) are found in both tumor cells and normal tissues

Tumor necrosis factors: Cytokines involved in cell proliferation and cell death. There are two types, alpha and beta

Tumors: Tumor is a general term for abnormal new growth initiated when a resting cell starts dividing. Used for both malignant (show invasiveness and metastasis) and benign (stays at site of origin) growth, here used interchangeably with cancer

Vaccines: Suspensions of attenuated microorganisms, antigenic proteins, synthetic molecules administered to prevent or treat infectious or other diseases

Vector: DNA from viruses or bacteria into which a gene of interest is inserted, capable of replicating