Immunology Flashcards
Intrinsic defense systems that act both independently and cooperatively to provide resistance to disease.
Immunity
Consists of the first line of defense, skin barriers, and the second line of defense, antimicrobial proteins and phagocytes. Always prepared to respond to protect the body from foreign substances.
Innate Defense System (Nonspecific)
Consists of the third line of defense. Responds to identified foreign substances.
Adaptive Defense System (Specific)
A functional system, rather than an organ system, involved in the immune response.
Immune System
Harmful or disease causing microorganisms.
Pathogens
Consists of skin, vaginal, and stomach secretions that inhibit bacterial growth.
Acid Mantle
Enzymes found in saliva, respiratory mucus, and lacrimal fluid of the eye that destroy bacteria.
Lysozymes
Protein that when dissolved in water forms a thick, sticky mucus that lines the digestive and respiratory passageway and traps many microorganisms.
Mucin
Broad-spectrum antimicrobial peptides secreted by mucous membranes and skin.
Defensins
Receptors that recognize molecules with specific shapes that are part of infectious organisms.
Pattern Recognition Receptors
A class of pattern recognition receptors that each recognize a particular class of attacking microbe.
Toll-like Receptors (TLRs)
The most abundant type of white blood cell. Becomes phagocytic on encountering infectious material in the tissues.
Neutrophils
The most voracious phagocytes. Derive from monocytes that leave the bloodstream and enter the tissues.
Macrophages
Consists of a foreign particle enclosed within a membrane-lined vesicle. Formed when a phagocyte engulfs particulate matter.
Phagosome
Formed when a phagosome fuses with a lysosome.
Phagolysosome
Promotes killing of pathogens by liberating a deluge of highly destructive free radicals, producing oxidizing chemicals, and increasing the phagolysosome’s pH and osmolarity, which activates other protein-digesting enzymes.
Respiratory Burst
Consists of complement proteins and antibodies.
Opsonins
Process where pathogens are coated with opsonins.
Opsonization
A group of defensive cells that can kill cancer cells and virus-infected body cells before the adaptive immune system is activated. Not phagocytic, but induce apoptosis.
Natural Killer (NK) Cells
A nonspecific response to any tissue injury. Prevents spread of damaging agents to nearby tissues, disposes of cell debris and pathogens, alerts the adaptive immune system, and sets the stage for repair. Signs include redness, heat, swelling, and pain.
Inflammation
A component of the inflammatory response. Release histamine.
Mast Cells
An inflammatory chemical released by mast cells.
Histamine
Other inflammatory chemicals (List 3)
Kinins, Prostaglandins, Cytokines
A group of plasma proteins that activate during the inflammatory response and form inflammatory chemicals
Complement
Caused by vasodilation of local arterioles. Brings more cells and chemicals of the immune system to the injured area.
Hyperemia
Fluid containing clotting factors and antibodies.
Exudate
Swelling
Edema
First phase of phagocyte mobilization. Injured cells release chemicals, causing neutrophils to enter the blood from red bone marrow.
Leukocytosis
Chemicals released by injured cells to increase the number of white blood cells.
Leukocytosis-inducing Factors
Second phase of phagocyte mobilization. Refers to the phenomenon of phagocytes clinging to the inner walls of the capillaries and post capillary venules.
Margination.
Third phase of phagocyte mobilization. Prompts the neutrophils to flatten and squeeze between endothelial cells of the capillary walls.
Diapedesis
Fourth phase of phagocyte mobilization. Neutrophils migrate up a gradient of inflammatory chemicals to the site of injury.
Chemotaxis
Inflammatory chemicals that act as homing devices for neutrophils and other WBCs
Chemotactic Agents
Substances that can mobilize the adaptive defenses. Large, complex molecules that are foreign.
Antigens
Antigens that are immunogenic and reactive. Includes virtually all foreign proteins, large polysaccharides, and some lipids and nucleic acids.
Complete Antigens
The ability to stimulate specific lymphocytes to proliferate.
Immunogenicity
The ability to react with the activated lymphocytes and antibodies release by immunogenic reactions.
Reactivity.
Small molecules that are not immunogenic, but can link up with the body’s own proteins. This combination is recognized by the adaptive immune system as foreign.
Hapten (Incomplete Antigen)
The part of the antigen that is immunogenic. Antibodies or lymphocyte receptors bind to these.
Antigenic Determinants
Type of cell surface glycoprotein that identify a cell as self.
Major Histocompatibility Complex (MHC) Proteins
Cells that oversee humoral immunity. Have receptors that are membrane-bound antibodies.
B lymphocytes (B Cells)
Cells that are non-antibody-producing and constitute the cellular arm of adaptive immunity
T lymphocytes (T Cells)
The ability of a lymphocyte to recognize its one specific antigen by binding to it.
Immunocompetence
The ability of a lymphocyte to be relatively unresponsive to self-antigens so that it does not attach the body’s own cells.
Self-Tolerance
Location where lymphocytes mature. Red bone marrow for B cells and thymus for T cells.
Primary Lymphoid Organs
All other organs involved in the lymphocyte activation process.
Secondary Lymphoid Organs
Characteristic of B and T cells that have not yet been exposed to antigens
Naïve
Occurs when a particular lymphocyte that has a receptor for a specific antigen and that antigen selects that lymphocyte for rapid proliferation.
Clonal Selection
A group of cells all descended from the same ancestor cell.
Clone
Members of lymphocyte clones that actually do the work of fighting infection.
Effector Cells
Members of lymphocyte clones that are able to respond quickly after any subsequent encounter with the same antigen.
Memory Cells
The first of two tests a developing T lymphocyte must pass. Ensures that only T cells with receptors that are able to recognize self-MHC proteins survive.
Positive Selection
The second of two tests a developing T lymphocyte must pass. Ensures that T cells to not recognize self-antigens displayed on self-MHC
Negative Selection
Cells that do not respond to specific antigens. Engulf antigens and then present fragments of them on their own surfaces where T cells can recognize them. Includes dendritic cells, macrophages, and B lymphocytes.
Antigen-Presenting Cells (APCs)
Cells that catch antigens with their long, wispy extensions, internalize the antigens by phagocytosis, and enter lymph nodes to present the antigens to T cells.
Dendritic Cells
Clone cells of activated B cells that differentiate. The antibody-secreting effector cells of the humoral response.
Plasma Cells
Clone cells of activated B cells that do not become plasma cells. Can mount humoral response if they encounter the same antigen again.
Memory Cells
The cellular proliferation and differentiation of naïve lymphocytes after initial exposure to their specific antigen. Has a lag period of 3-6 days.
Primary Immune Response.
Occurs when someone is reexposed to the same antigen. Faster, more prolonged, and more effective than the primary immune response.
Secondary Immune Response
Provided by the memory cells after the immune system has already been primed to the specific antigen.
Immunological memory
Occurs when the B cells encounter antigens and produce antibodies against them. Naturally acquired when exposed to bacterial or viral infection. Artificially acquired when receiving a vaccine.
Active Humoral Immunity
Occurs when ready-made antibodies are introduced into the body. Does not activate B cells. Protection ends when these “borrowed” antibodies naturally degrade. Naturally occurs when mother passes antibodies to baby through placenta or in breastmilk. Artificially occurs through plasma donation.
Passive Humoral Immunity
Proteins secreted in response to an antigen by effector B cells. Bind specifically with that antigen.
Antibodies. (AKA immunoglobulins)
Consists of four looping polypeptide chains linked together by disulfide bonds. Has two identical halves.
Antibody Monomer
Two of the polypeptide chains that are identical to each other. Have a flexible hinge region in the middle.
Heavy (H) chains
Two of the polypeptide chains that are identical to each other. Half as long as each H chain.
Light (L) chains
Region of the polypeptide chain that is different for antibodies responding to different antigens.
Variable (V) region
Region of the polypeptide chain that is the same in all antibodies of a given class.
Constant (C) Region
Formed by the combined V regions of the light and heavy chains. Fits a specific antigenic determinant.
Antigen-Binding Site
The first immunoglobin class secreted by plasma cells during the primary response. Readily activates complement. Exists in monomer and pentamer forms. The monomer serves as an antigen receptor on the B cell surface. The pentamer circulates in blood plasma. Numerous antigen-binding sites make it a potent agglutinating agent.
IgM
The dimer, found in body secretions such as saliva, sweat, intestinal juice, and milk. Helps stop pathogens from attaching to epithelial cell surfaces.
IgA
Found on the B cell surface. Functions as a B cell antigen receptor. Monomer
IgD
The most abundant antibody in plasma, accounting for 75-85% of circulating antibodies. The main antibody of both secondary and late primary responses. Readily activates complement. Protects against bacteria, viruses, and toxins circulating in blood and lymph. Crosses the placenta and confers passive immunity from the mother to the fetus.
IgG
Stem end binds to mas cells or basophils. Antigen binding to its receptor end triggers these cells to release histamine and other chemicals that mediate inflammation and an allergic reaction. Secreted by plasma cells in skin, mucosae of the gastrointestinal and respiratory tracts, and tonsils. Only traces are found in plasma. Levels rise during severe allergic attacks or chronic parasitic infections of the gastrointestinal tract.
IgE
Formed when an antibody interacts with its specific antigen.
Antigen-Antibody Complex
Occurs when antibodies block specific sites on viruses or bacterial exotoxins, preventing them from binding to receptors on tissue cells.
Neutralization
Occurs when cell-bound antigens on foreign cells clump up due to cross-linking of antigen-antibody complexes. (Antibodies have more than one antigen-binding site.)
Agglutination
Occurs when soluble molecules are cross-linked into large complexes that settle out of solution.
Precipitation
Occurs when several antibodies bind close together on the same cell causing the complement-binding sites on their stem regions to align and activate. Membrane attack complexes may insert into the antigenic cell’s surface, triggering cell lysis.
Complement Activation
Pure antibody preparations specific for a single antigenic determinate. Used commercially in research, clinical testing, and treatment.
Monoclonal Antibodies
Naïve T cells that usually become helper T cells, which help activate B cells, other T cells, and macrophages and direct the adaptive immune response. May also become regulator T cells, which moderate the immune response. Only bind to antigens on class II MHC proteins.
CD4 Cells
Naïve T cells that become cytotoxic T cells that destroy cells in the body that harbor anything foreign. Activated by antigen fragments found on class I MHC proteins.
CD8 Cells
Found on the surface of virtually all body cells except red blood cells. Has a groove that holds an antigen.
Class I MHC proteins
Antigens that are displayed on class I MHC proteins. Fragments of proteins synthesized inside the cell.
Endogenous Antigens
Typically found only on the surfaces of cells that present antigens to CD4 cells: dendritic cells, macrophages, and B cells.
Class II MHC proteins
Antigens that are displayed on class II MHC proteins. Come from antigens found outside the cell that have been engulfed by the cells that displays them.
Exogenous Antigens
Receptors that bind to antigen-MHC complexes on the surface of an APC.
T Cell Antigen Receptors (TCRs)
Other molecules that appear on the surfaces of APCs in tissues that are damaged or invaded by pathogens. Binds to T cell to initiate proliferation.
Co-Stimulatory Signals
The state of unresponsiveness to an antigen. Occurs when a T cell binds to an antigen without receiving the co-stimulatory signal.
Anergy
Chemical messengers involved in cellular immunity. Mediators that influence cell development, differentiation, and responses in the immune system.
Cytokines
Cytokine released by macrophages to stimulate T cells in release IL-2 and to synthesize more IL-2 receptors.
Interleukin 1 (IL-1)
Cytokine released by T cells and helps set up positive feedback cycle that encourages activated T cells to divide more rapidly.
Interleukin 2 (IL-2)
Cells that help activate B and T cells, and induce B and T cells to proliferate.
Helper T cells (TH)
Antigens that active B cells without the help of T cells.
T Cell-Independent Antigens
Antigens that require T cell help to activate the B cells to which they bind.
T Cell-Dependent Antigens
Activated CD8 cells. Can directly attack and kill other cells. Roam the body, circulating in and out of the blood and lymph in search of body cells displaying antigens that the cells recognize.
Cytotoxic T cells (Tc)
Release. by Tc cells. Create large pores in the target cell’s membrane.
Perforins
Released by Tc cells. Enter the target cell through pores created by perforins and induce apoptosis.
Granzymes
Process of NK cells and Tc Lymphocytes roaming the body and adhering to and crawling over the surfaces of other cells, examining them for markers they might recognize.
Immune Surveillance
Cells that dampen the immune response by direct contact or by releasing inhibitory cytokines.
Regulatory T Cells (Treg)
