Term
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Definition
Integrins/Selectins
These are the molecules that mediate the binding of cells to other cells or to extracellular matrix molecules such as fibronectin |
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Definition
| Variants of a single genetic locus |
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Definition
| Fragments of complement proteins released during activation. Result in increased vascular permeability and attract leukocytes. |
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Definition
| A protein produced as a result of interaction with an antigen. The protein has the ability to combine with the antign that stimulated its production. |
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Definition
| A substance that can react with an antibody. Not all antigens can induce antibody production; those that can are also called immunogens. |
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Definition
| Strictly, a bursa-derived cell in avian species and, by analogy, a cell derived from the equivalent of the bursa in nonavian species. B cells are the precursors of plasma cells that produce antibody. |
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Term
| Cell-mediated (cellular) immunity |
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Definition
| Immunity in which the participation of lymphocytes and macrophages is predominant. Cell-mediated immunity is a term generally applied to the type IV hypersenstivity reaction |
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Definition
| Low-molecular weight proteins that stimulate leukocyte movement. |
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Definition
| A process whereby phagocytic cells are attracted to the vicinity of invading pathogens. |
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Definition
| A set of plasma proteins that is the primary mediator of the antigen-antibody reaction. |
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Definition
| The lysis of bacteria or of cells such as tumor or RBC by insertion of the membrane attack complex derived rom complement activation. |
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Definition
| T cells that can kill other cells, eg, cells infected with intracellular pathogens. |
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Definition
| Bacterial toxins released from damaged cells. |
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Definition
| Site on an Ag recognized by an Ab. Also know as an antigenic determinant. |
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Definition
| A molecule that is not immunogenic by itself but can react with specific Ab |
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Term
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Definition
| Sharing transplantation Ag |
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Definition
| Pertaining to immunity in a body fluid and used to denote immunity mediated by Ab and complement. |
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Term
| Type I Hypersensitivity Reaction |
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Definition
Antibody-Mediated
Immediate
IgE antibody is induced by allergen and binds via its Fc receptor to mast cells and eosinophils. After encountering the Ag again, the fixed IgE becomes cross-linked, inducing degranulation and release of mediators, especially histamine.
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Term
| Type II Hypersensitivity Reaction |
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Definition
Antibody-Mediated
Antigens on a cell surface combine with Ab, which leads to complement-mediated lysis (eg. transfusion or Rh reactions) or othe rcytotoxic membrane damage (eg, autoimmune meolytic anemia). |
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Term
| Type III Hypersensitivity Reaction |
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Definition
Antibody-Mediated
Ab-Ag immune complexes are deposited in tissues, complement is activated and PMN (neutrophil) cells are attracted to the site, causing tissue damage. |
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Term
| Type IV Hypersensitivity Reaction |
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Definition
Cell-Mediated
Delayed
T lymphocytes, sensitized by an Ag, release cytokines upon second contact with the same Ag. The cytokines induce inflammation and actiavte macrophages. |
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Term
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Definition
| Development of resistance (immunity) to a foreign substance (infectious agent). it can be Ab-mediated (humoral) or cell-mediated (cellular) or both |
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Definition
| Nonspecific resistance not acquired through contact with an Ag. it includes skin and mucous membrane barriers to infectious agents and a variety of nonspecific immunologic factors and it may vary with age and hormonal/metabolic activity. |
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Term
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Definition
| Protection acquired by deliberate introduction of an Ag into a responsive host. Active immunity is specific and is mediated by either Ab or lymphoid cells (or both). |
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Definition
| A glycoprotein, composed of H and L chains, that functions as Ab. All Ab are immunoglobulins, but not all immunoglobulins have Ab function. |
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Term
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Definition
| A subdivision of immunoglobulin molecules based on structual (amino acid sequence) differences. In humans, there are five immunoglobulin classes (IgG, IgM, IgA, IgE, and IgD) |
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Term
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Definition
| A subdivision of the classes of immunoglobulins based on structural differences in the H chain. For human IgG, there are four subclasses - IgG1, IgG2, IgG3, IgG4 |
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Definition
| Local accumulation of fluid and cells after injury or infection |
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Definition
| One of a heterogeneous group of low-molecular weight proteins elaborated by infect host cells that protect noninfected cells from viral infection. Interferons, which are cytokines, also have immunomodulating functions |
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Definition
| General term for a white blood cell. |
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Term
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Definition
A mononuclear cell 7-12 [image]m in diameter containing a nucleus with densely packed chromatin and a small rim of cytoplasm. Lymphocytes include the T cells and B cells, which have primary roles in immunity.
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Term
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Definition
| A phagocytic mononuclear cell derived from bone marrow monocytes and found in tissues and at the site of inflammation. Macrophages serve accessory roles in immunity, particularly as antigen presenting cells (APCs) |
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Term
| Major Histocompatibility Complex |
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Definition
| MHC - a cluster of genes located in close proximity, eg, on human chromosome 6, that encode the histocompatibility Ag (MHC molecules) |
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Term
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Definition
| The end product of activation of the complement cascade, which contains C5, C6, C7, C8 and C9. The MAC makes holes in the membranes of gram-negative bacteria, killing them and, in RBC or other cells, resulting in lysis. |
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Term
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Definition
| Each B lymphocyte produces Ab of a single specificity. However, normal B cells do not grow indefinitely. If B cells are fused to a myeloma cell by somatic cell hybridization and fused cells that secrete the desired Ab specificity are selected, an immortalized Ab-producing cell line, known as a hybridoma, is obtained, and these hybrid cells produce monoclonal Ab. |
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Term
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Definition
| A circulating phagocytic blood cell that develops into tissue macrophages |
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Term
| Natural Killer (NK) cells |
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Definition
| Large granular lymphoid cells with no known Ag-specific receptors. They are able to recognize and kill certain abnormal cells (tumor cells, for example) and also activate the innate response. |
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Definition
| A substance capableof enhancing phagocytosis. Ab and complement are two main opsonins. |
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Term
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Definition
| The coating of an Ag or particle (eg infectious agent) by substances such as Ab, Complement components, fibronect and so forth, that facilitate uptake of the foreign particle into a phagocytic cell. |
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Term
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Definition
| A terminally differentiated B cell that secretes Ab. |
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Term
| Polymorphonuclear (PMN) cell |
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Definition
| Also known as a neutrophil or granulocyte, a PMN is characterized by a multilobed nucleus. PMNs migrate from the circulation to a site of inflammation by chemotaxis and are phagocytic for bacteria and other particles. |
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Term
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Definition
| T lymphocyte - a thymus derived cell that participates in a variety of cell-mediated immune reactions. |
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Term
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Definition
| Developing T cells found in the thymus. |
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Term
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Definition
| Induction of immunity by injected a dead or attenuated form of a pathogen. |
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