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Biology Test #3

Terms in this set (19)

Epitope
a molecular region on the surface of an antigen capable of eliciting an immune response and of combining with the specific antibody produced by such a response —called also determinant, antigenic determinant
Antigen
is any substance which provokes an adaptive immune response.[1] An antigen is often foreign or toxic to the body (for example, a bacterium) which, once in the body, attracts and is bound to a respective and specific antibody.
MHC
Is a set of cell surface molecules encoded by a large gene family in all vertebrates which controls a major part of the immune system. MHC molecules mediate interactions of leukocytes, also called white blood cells (WBCs), which are immune cells, with other leukocytes or with body cells. MHC determines compatibility of donors for organ transplant as well as one's susceptibility to an autoimmune disease via crossreacting immunization. In humans, MHC is also called human leukocyte antigen (HLA).
Antibody
Is a large Y-shape protein produced by plasma cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, called an antigen.
Cytokines
Are a broad and loose category of small proteins (~5-20 kDa) that are important in cell signaling. They are released by cells and affect the behavior of other cells, and sometimes the releasing cell itself.
Macrophage
a large white blood cell, occurring principally in connective tissue and in the bloodstream, that ingests foreign particles and infectious microorganisms by phagocytosis.
-Monocytes are agranular leukocytes which originate in the bone marrow
Monocytes
A white blood cell that has a single nucleus and can take in (ingest) foreign material.
-bone marrow
B-Cells:
-are a type of lymphocyte in the humoral immunity of the adaptive immune system. B cells can be distinguished from other lymphocytes, such as T cells and natural killer cells (NK cells), by the presence of a protein on the B cells outer surface known as a B cell receptor (BCR). This specialized receptor protein allows a B cell to bind to a specific antigen.

-The principal functions of B cells are to make antibodies against antigens, to perform the role of antigen-presenting cells (APCs), and to develop into memory B cells after activation by antigen interaction-bone marrow
T-Cells
-bone marrow and mature in tymus
T helper cells (TH cells)
assist other white blood cells in immunologic processes, including maturation of B cells into plasma cells and memory B cells, and activation of cytotoxic T cells and macrophages
Cytotoxic T cells
destroy virally infected cells and tumor cells, and are also implicated in transplant rejection.
Memory T cells
are a subset of antigen-specific T cells that persist long-term after an infection has resolved.
Regulatory T cells (Treg cells),
Formerly known as suppressor T cells, are crucial for the maintenance of immunological tolerance. Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress auto-reactive
Natural killer T cells
-Bridge the adaptive immune system with the innate immune system. Unlike conventional T cells that recognize peptide antigens presented by major histocompatibility complex (MHC) molecules, NKT cells recognize glycolipid antigen presented by a molecule called CD1d.
-Once activated, these cells can perform functions ascribed to both Th and Tc cells (i.e., cytokine production and release of cytolytic/cell killing molecules). They are also able to recognize and eliminate some tumor cells and cells infected with herpes viruses.
antigen-presenting cells:
...
B-cells
have receptors for antigens that are immunoglobulin molecules that are shown on cell as proteins in the membrane which are specific for a particular epitope of antigen; naive B-cells encounter antigens in the secondary lymph; B-cell becomes activated when immunoglobulin molecules on membrane bind with specific epitope of antigen and when they receive signals usually cytokines secreted by helper T-cells; once activated they multiply into plasma cells and memory cells
plasma cells:
produced when B-cell is activated; secrete antibody specific to antigen working against it; antibodies enter lymph and blood and bind to appropriate epitopes of antigen encountered anywhere in the body
helper T-cells:
activated by T-cell receptors bound to peptides displayed on self-MHC class II proteins on dendritic cells which results in either becoming memory cells or activated cells; activated helper T-cells secrete cytokines; cytokines are important signaling molecules that bind to receptors of immune system cells either activating or differentiating them; helper T-cells mediate immune response and determine if it humoral or cellular
cytotoxic T-cells:
recognize "altered-self" cells; receptors of cytotoxic T-cells recognize peptides of antigens from the "self" bound to MHC class I proteins, this antigen may be a self protein or a viral protein produced in a virally infected cell or unusual protein produced in a cancerous cell; dendritic cells present antigens that activate Tc cells in other words Tc cell binds antigen through TCR and CD8 site on the dendritic cell inducing clonal expansion which produces activated cells or memory cells, these activated cells then circulate body and target host cells with same combination of foreign peptide and cause it to go through apoptosis.
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