Innate Immunity (Lec. 19) Flashcards
Define opsonization
A process by which a pathogen is marked for phagocytosis through coating of a target cell with antibodies
Define opsonin
An extracellular protein (an antibody or a complement protein) which binds to foreign microorganisms, substances, or cells and induces phagocytosis
Define immunity
The development of specific resistance to a foreign agent (requires the recognition of self and non-self through surface markers)
Define immunocompromised
An individual who does not have a fully functioning immune system
Define an immune response
A physiological process coordinated by the immune system to eliminate foreign antigens
Define antigen
Any substance that, if presented in the right context, may trigger an immune response
Define cytokine
A signaling protein that’s secreted by one cell that sends a message to another cell and allows cells to communicate
Define epitope
A specific part of an antigen that interacts with the antibody or T cell receptor
Define interferon
a protein released by animal cells, usually in response to the entry of a virus, which has the property of inhibiting virus replication
Define margination
the movement of WBCs and platelets toward the walls of a blood vessel, and the formation of a margin
Define diapedesis
the passage of WBCs through the intact walls of capillaries
Compare and contrast innate and adaptive immunity
Innate immunity: nonspecific; phagocytes are primary effective cells; all eukaryotic organisms have it fully developed at birth; generalized immediate responses; no memory
Acquired/adaptive immunity: specific; only in vertebrate animals and matures over time; tailored responses that require 4-7 days; primary effector cells and B and T lymphocytes (B cells and T cells; exhibits memory
Both recognize and eliminate diverse pathogens, and discriminate between self and foreign antigens
Describe mechanical barriers and provide an example
Cilia, peristalsis, coughing, sneezing, defecation, urination. Bodily processes that have to be overcome by a pathogen that wants to colonize certain body sites.
Describe chemical barriers and provide an example
Mucus, tears, saliva, sweat, stomach acid, ear wax. Products of the body that pathogens have to overcome.
Describe physical barriers and provide an example
Skin, epithelial layers/mucous membranes (respiratory, GI tract, GU tract)
Identify a biological barrier to infection
Normal microbiota
Describe lymph and how it is collected and filtered
Plasma exits the capillaries; cells and tissues are bathed in interstitial fluid; lymph nodes filter lymph before returning it to the circulatory system (it’s only called “lymph” when it’s coming out of cells and tissues and going back to lymph nodes)
Name the primary and secondary lymphoid tissues and describe their basic roles
Primary: thymus (where T lymphocytes develop) and bone marrow (where B lymphocytes develop)
Secondary: Encapsulated: lymph nodes, spleen; Diffuse: MALT (mucosa-associated lymphoid tissue; immune cells that underlie all mucosal linings, like your tonsils and Peyer’s patches), GALT (gut-associated lymphoid tissue)
List the three immune cells that are phagocytes
Neutrophils: 1st WBC to leave blood and move into injured tissues
Macrophages/monocytes: called macrophages when they’re in tissues and monocytes when they’re in blood; presents antigen to T cells
Dendritic cells: reside in tissues and lymph nodes; present antigen to T cells
Describe phagocytosis and its role in innate immune function
A mechanism for ingesting particulate material; it’s some WBC’s only function to protect the body from invading pathogens. No memory after exposure.
Describe the 2 ways phagocytes recognize pathogens
Opsonization: something is covered in opsonins and is then phagocytized
Opsonization-independent recognition: phagocytes have pattern-recognition receptors (PRRs) or toll-like receptors (TLRs) which recognize Pathogen-associated molecular patterns (PAMPs), like molecules that are common to bacteria, viruses, and other pathogens
Describe the types of cytokines and their function
Chemokines: a signaling molecule that is an attractant to another cell (can recruit WBCs and other parts of the immune system to them)
Interleukins: a cytokine that is secreted by one leukocyte that is directed with a message toward another leukocyte; stimulate an immune response
Interferons: typically released by cells of the immune system or virally-infected cells;
Describe the complement system and its 3 functions
A group of plasma proteins that are produced by the liver and circulate in inactive form; once activated (classical method of activation: antibodies), have three specific functions:
1. Opsonization: deposit of complement on pathogen surface which enhances phagocytosis
2. Formation of membrane attack complex (MAC) which results in cytolysis
3. Promote inflammation
List the primary goals of inflammation and describe its 3 stages.
Nonspecific response to tissue injury; important part of innate immune defense. Recruits immune defenses to the injury, limits the spread of infectious agents, and delivers oxygen and nutrients needed for recovery. Stage 1: vasodilation; exudate accumulates. Stage 2: Leukocyte recruitment (chemokines recruit WBCs) and margination (adhesion to the walls of the blood vessel), diapedesis (WBCs squeezing through gaps in the walls of blood vessels), and extravasation (WBCs exiting blood vessel and entering tissue). Stage 3: Resolution/repair/healing (angiogenesis builds new blood vessels, blood clots dissolve, WBCs undergo apoptosis, pus may form)
