Antigens that can stimulate antibody production only with help from T helper cells.
An immune reponse in which an antibody binds to and blocks the ativity of an antigen.
The process by which a pathogen is marked for ingestion and destruction by a phagocyte.
An antibody-mediated immune response in which bacteria or viruses are clumped together, effectively neutralized, and opsonized.
An immune response in which antigen-antibody complexes activate complement proteins.
Membrane Attack Complex
The complex of terminal complement components that forms a pore in the membrane of the target cell, damaging the membrane and leading to cell lysis.
The collective action of antibodyies, complement, and phagocytes. Microbes coated with antibodies and complement proteins adhere to blood vessel walls, making the pathogens easier prey for phagocytic cells circulating in the blood.
An antigen that will stimulate the formation of antibodies without the assistance of T helper cells.
A localized region on the surface of an antigen that is chemically recognized by antibodies; also called antigenic determinant.
Immunity provided by the body producing its own antibodies against a particular antigen; results from exposure to the antigen via infection or vaccine.
White blood cells that are responsible for combating infection by parasites in the body.
Natural Killer Cells
A nonspecific defensive cell that attacks tumor cells and destroys infected body cells, especially those harboring viruses.
The normal situation whereby a person's immune system does not respond to constituents of the person's body.
An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellualar chromosomes; an important class of cancer-causing viruses.
A surface protein, present on most helper T cells, that binds to class II MHC molecules, enhancing the interaction between the T cell and an antigen-presenting cell.
A surface protein, present on most cytotoxic T cells, that binds to class I MHC molecules, enhancing the interaction between the T cell and a target cell.
A group of about 50 different proteins secreted by blood vessel endothelial cells and monocytes. Theses molecules bind to receptors on many types of leukocytes and induce numerous changes central to inflammation.
Cytotoxic T Cell
A T lymphocyte that directly attacks and destorys infected body cells, cancerous cells, and the cells of transplanted tissues.
A type of T cell that is required by some B cells to help them make antibodies or that helps other T cells respond to antigens or secrete lymphokines or interleukins.
Antigen recptores on a T cell. Unlike antibodies, T cell recptors are never prduced in a secreted form.
A type of lymphocyte responsible for cell-mediated immunity that differentiates under the influence of the thymus.
Nonspecific Immune System Cells
Immune system that does not differentiate between one infectious agent and another. Has two lines- internal and external.
The body's defensive reaction to invasion by bacteria, viral agents, or other foreign substances.
Lymphocyte that matures in the bone marrow and later produces antibodies; responsible for humoral immunity.
The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids.
Cell Mediated Response
The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells.
A protein secreted by a cytotoxic T-cell that lyse (ruptures) an infected cell by perforting its membrane.
Antigen Presenting Cells
A cell that facilitates the immune response by holding antigens on its surface and presenting them to lymphocytes.
Primary Immune Response
The initial acquired immune response to an antigen, which appears after a lag of about 10 to 17 days.
Secondary Immune Response
The adaptive immune response provoked by a second exposure to an antigen. It differs from the primary response by starting sooner and building more quickly.
Molecules that set the body's thermostat to a higher temperature. They are released by certain leukocytes.
Chemical alarm signal released by mast cells that causes blood vessels to dilate during an inflammatory response.
A White Blood cell that enter damaged tissues and enhance the inflammation process and contain histamine and heparin.
Nonspecific defense against infection, characterized by redness, heat, swelling, and pain.
Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
The most abundant type of white blood cell. Neutrophils are phagocytic and tend to self-destruct as they destroy foreign invaders, limiting their life span to a few days.
An enzyme that lyses bacterial cell walls. Lysozyme is produced in the end stages of the lytic cycle so that new viral particles can escape their host; it is also found in human tears and human saliva.