Chapter 12 Immunology Flashcards
(126 cards)
the work of Jenner and Pasteur
principle of prior exposure to related or attenuated microorganisms leading to protective immunity
major histocompatibility complex (MHC) proteins
The immune system’s most important role is to distinguish between “self” and “nonself” and to remove foreign molecules and organisms that invade the body.
Characteristics of self are attributed to macromolecules on cell surfaces
antigen
Pathogens, proteins from a genetically different individual, or other substances
antigenicity
The degree to which an antigen can induce an immune response
The main parts of the immune system where leukocytes are generated:
the thymus,
the bone marrow,
the liver, and
the spleen.
Innate immunity
provides the first line of defense against invading foreign substances. This immunity consists of physical, biochemical, or cellular agents which are natural body defenses that detect and neutralize potential invaders.
reactive proteins
complement proteins
circulate in blood and tissue spaces in inactive forms
These proteins adhere to the surface of the invading organisms and facilitate an attack by phagocytic cells.
interferons
chemicals that carry out communication among cells
three types of interferons:
alpha,
beta, and
gamma.
neutrophils
macrophages and granulocytes
Macrophages and granulocytes release cytokines
Macrophages and granulocytes also initiate phagocytosis to engulf these foreign cells.
epitope
antigen fragment
2 kinds of acquired immune response
Cell-mediated response
Antibody-mediated response
Cell-mediated response
where most types of specialized lymphocytes, called T cells, stimulate the immune response through several pathways. They secrete cytokines (different from interferons) that stimulate the immune response in other cells. T cells release cytotoxic molecules that destroy foreign cells, cancer cells, and the body’s own injured cells. T cells are also necessary to stimulate B cells, inducing them to evolve into plasma cells for the production of antibodies.
Antibody-mediated response
where plasma cells (stimulated B cells) secrete antibodies that neutralize or destroy the infectious agents. The antibody-mediated response is often called the humoral immune response because the antibody-antigen interaction occurs in the fluids outside the cells; humoral means “body fluids.”
Amplification
the second step, is where the immune response increases in magnitude. Pathogen-specific T-cells proliferate; B-cells mature into plasma cells, magnifying the antibody titer; and the activating signal is transmitted from the T cell receptor to other molecules and cells in the animal.
Chemokines
mediate cell traffic, directing the movement of the immune cells throughout the lymphatic system.
cytokines
induce the antigen-specific T cells to proliferate and attack the pathogen, whereas others produce the redness, pain, and heat that are associated with the body’s inflammatory response.
resolution
the immune system has eliminated the threat to the body. The infected cells, parasites, or pathogens are dead
Macrophages
are a component of the innate immune system. Macrophages are phagocytes which engulf foreign materials, digest them into smaller pieces (breaking proteins into peptides, for example), and present these antigens to other cells of the immune system. As antigen-presenting cells (APCs), they promote the activities of cells in the acquired immune system. They offer a nonspecific response to substances recognized as nonself and often initiate the inflammatory response that will ultimately rid the body of the invading agent.
Granulocytes
include neutrophils, eosinophils, mast cells, and basophils. Neutrophils destroy invading cells by engulfing them (for example, bacteria) or releasing the contents of lysosomes onto them (for example, parasites and cancer cells). They respond to cytokines and other signals from antigen-presenting cells. They support the activities of cells in the acquired immune system. Mast cells and eosinophils play a role in inflammatory and allergic reactions. They release potent inflammatory mediators, such as histamine.
Dendritic cells
have a major role in initiating an immune response. Their role is similar to that of macrophages. They act as antigen-presenting cells, trapping the antigens on their surface, migrating to lymph nodes, and presenting the antigens to other lymphoid cells to initiate a response.
B lymphocytes (B cells)
provide antibody-mediated immunity. These cells originate from bone marrow in higher vertebrates and from an organ called the bursa of Fabricius in birds. (B cells were named for this bursa.) When activated, B cells develop into plasma cells that produce and secrete antibodies that bind to antigens and mark them for destruction. B cells and plasma cells are part of the humoral response of the acquired immune system.
T lymphocytes (T cells)
develop in the thymus and provide cell-mediated immunity. They attack and destroy diseased cells which they identify as foreign. T cells have special molecules on their surface (T-cell receptors), which help them recognize and attach to antigens.
Antibodies
are immunoglobulins (Ig, pronounced as the letters “I” and “G”), which are glycoproteins (protein + carbohydrate) that bind to antigens in what is known as the antibody-antigen complex.
five classes of immunoglobulins in mammals
IgG, IgM, IgA, IgE, and IgD.
