immune response that is specific to a particular pathogen and arises after an immunizing event, such as vaccination or an infection
complement pathway in which signal molecules bind to the surface of all cells. However, only host cells possess the cell surface proteins that prevent the signal cascade.
type of white blood cell that releases histamine and heparin to promote inflammatory reactions such as in allergic reactions, anaphylaxis, and asthma. Basophils make both histamine and serotonin.
complement pathway activated when complement signal proteins encounter an antibody bound to an antigen, which could be a potential pathogen or allergen
collection of immune system pathways and complement proteins that protect the body from microbes by enhancing the function of leukocytes and antibodies
shedding of the outermost layer of skin to protect the body from microbes bound to the skin
leukocyte that contains granules and releases cytotoxic chemicals to kill large parasites. It also aids in the regulation of allergies and asthma.
local response to injured tissue that results in an increased blood flow to the affected site and triggers a cell-mediated immune response if the second line of defense fails
nonspecific immune response, including chemical and physical barriers and internal cellular and chemical defenses
class of signaling proteins secreted by host cells when pathogens or cancerous cells are detected
complement pathway activated when the signal protein mannan-binding lectin binds to mannose residues that are found on the surface of most organisms' cells but that are prominently displayed on pathogens
type of formed element in blood that aids the immune process and protects the body from infections and foreign invasion. Leukocytes lack hemoglobin and are therefore colorless, or "white," which is why they are also referred to as white blood cells.
one of a family of several different types of leukocytes, including B cells, T cells, and natural killer (NK) cells. Lymphocytes are found in lymphoid organs, such as lymph nodes.
organelle in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane
enzyme produced by many types of cells in the body that breaks down the bonds that make up bacterial cell walls
membrane attack complex (MAC)
aggregate of complement proteins C5–C9 that is formed in the membrane of a target cell and mediates cell lysis by formation of a membrane pore
mucosa-associated lymphoid tissue (MALT)
clusters of immune cells located in the mucous areas of the body (lungs, eyes, nasal passages) that protect the body from infection by pathogens
most common type of leukocyte in the body. It migrates from the bloodstream to carry out phagocytosis at the site of an injury.
molecules detected by the immune system that signal to immune cells the molecule may be an invading pathogen
coating the surface of an antigen with opsonins to enhance the interaction between phagocytic cells and the antigen
pattern recognition receptor
cellular receptor that binds specifically to molecules commonly associated with pathogens in order to signal infection to leukocytes in an innate immune reaction
small cluster of immune cells located along the wall of the small intestine that prevents infection by pathogens passing through the alimentary canal
molecules detected by the immune system that signal to immune cells the molecule is a part of the host body