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Immune System Ch 21

A&P - Wk 7

What are the 2 intrinsic defense systems that act both independently and cooperatively to provide resistance to disease? innate (nonspecific) defense system adaptive (specific) defense system
Which defense system is always prepared, responds in minutes; and has 2 lines of defense? innate (nonspecific) defense system
Which defense system attacks particular foreign substances and takes its time and provides the body's third line of defense? adaptive (specific) defense system
What is the hallmark of the second line of defense of the innate defense system? inflammation
Which line of defense in the innate defense system uses antimicrobial proteins, phagocytes, and other cells to inhibit the invaders' spread? 2nd line of defense
What is the 1st line of defense in the innate defense system? external body membranes - intact skin and mucosae
What are the 'structures' of the immune system? diverse array of molecules plus trillions of immune cells (esp lymphocytes)that inhabit lymphoid tissues and circulate in body fluids
The innate defenses reduce the workload of the adaptive system how? by preventing the entry and spread of microorganisms in the body
What skin secretion contains chemicals that are toxic to bacteria and inhibit its growth? sebum
What secretes a concentrated hydrochloric acid solution and protein-digesting enzyme that kill microorganisms? the stomach mucosa
What secretion contains lysozyme? saliva and lacrimal fluid of the eye
What happens when the surface barriers are breached? the internal innate defenses come into play
Where do the chief phagocytes (macrophages) derive from? white blood cells called monocytes that leave the bloodstream, enter the tissues, and develop into macrophages
Which macrophages wander thru the tissue spaces in search of cellular debris or "foreign invaders"? free macrophages
What are Kupffer cells in teh liver and microglia of the brain? fixed macrophages
How do eosinophils defend against parasitic worms? They position themselves against the worm and discharge the destructive contents of their large cytoplasmic granules all over the worm
What is a phagosome fused with a lysosome? a phagolysosome
What must occur in order for a phagocyte to accomplish ingestion? adherence-the phagocyte must first adhere or cling to the pathogen
What is the process called when complement proteins or antibodies coat foreign particles to make adherence more probable and more efficient? opsonization
What is produced when the macrophage is stimulated by chemicals released by immune cells, activating additional enzymes? respiratory burst, an event that liberates a deluge of free radicals with potent cell-killing ability
What is more widespread cell killing accomplished by? oxidizing chemicals - H2O2 and a substance identical to household bleach
What is another mechanism of killing triggered by the respiratory burst involving K+? K+ enters phagolysosome, the pH rises and the phagolysosome becomes hyperosmotic, which activated protein-digesting enzymes that digest the invader
What do phagocytes do to kill their targets when the target is too big to ingest? release their toxic chemicals into teh extracellular fluid
Macrophages are not destroyed in the process of killed ingested or extracellular targets, but which WBC is destroyed in the process? neutrophil
What is a unique group of defensive cells that can lyse and kill cancer cells and virus-infected body cells before the adaptive immune system is activated? natural killer (NK) cells
NK cells are part of a small group of large granular lymphocytes and are sometimes called the _______ of the defense system. pit bulls
How do NK cells eliminate a variety of infected or cancerous cells? by detecting the lack of "self" cell surface receptors and by recognizing certain surface sugars on the target cell
Are NK cells phagocytic? No, they use direct contact and induce the target cell to undergo apoptosis (programmed cell death)
When is the inflammatory response triggered? Whenever body tissues are injured by physical trauma, intense heat, irritating chemicals, or infection by viruses, fungi, or bacteria
What 3 beneficial effects does the inflammatory response provide? 1) prevents spread of damaging agents to nearby tissues 2) disposes of cell debris and pathogens 3) sets the stage for repair
What are the 4 cardinal signs of short-term, or acute, inflammation? 1) redness 2) heat 3) swelling 4) pain
If a joint is inflamed what may be temporarily hampered and why? joint movement to allow the joint to rest, which aids healing
What do some consider to be a 5th cardinal sign of acute inflammation? impairment of function
What are macrophages and cells of certain boundary tissues such as epithelial cells lining the gastrointestinal and respiratory tracts called that bear surface membrane receptors? Toll-like receptors (TLRs)
What plays a central role in triggering immune responses? Toll-like receptors (TLRs)
How many types of TLRs have been identified, each recognizing a specific class of attacking microbe? 10
Once activated, a TLR triggers the release of chemicals called cytokines that promote inflammation and attract what to the scene? WBCs
What other cells besides macrophages possess a recognition "tool" in the innate system? Mast cells, a key component of the inflammatory response, release the potent inflammatory chemical histamine
What do the following have in common? injured and stressed tissue cells, phagocytes, lymphocytes, basophils, and blood proteins they are all sources of inflammatory mediators
Sources of inflammatory mediators include: histamine, cytokines, kinins, prostaglandins, leukotrienes, and complement
All mediators cause small blood vessels in the injured area to do what? dilate, accounting for the redness and heat of an inflamed region
What is the condition called where blood flows into an injured area causing head and redness? hyperemia
What is fluid containing clotting factors and antibodies that seeps from the blood into the tissue spaces? exudate
What causes the local edema (swelling) that presses on adjacent nerve endings, contributing to a sensation of pain? exudate
What does the release of bacterial toxins and the sensitizing effects of released prostaglandins and kinins contribute to? pain
How do aspirin and some other anti-inflammatory drugs produce pain reducing effects? by inhibiting prostaglandin synthesis
What bacteria have evolved enzymes to break down a clot allowing its bacteria to spread? streptococcus
What enters inflammatory sites where an epithelial barrier has been breached? B-defensins
What broad-spectrum antimicrobial chemicals are continuously present in epithelial mucosal cells in small amounts to help maintain sterile environment of the body's internal passageways? B-defensins
When is B-defensin output increased dramatically, to control bacterial and fungal colonization? when the mucosal surface is abraded or penetrated and tissues become inflamed
If an inflammation is provoked by pathogens, what type of plasma proteins is activated? complement
What chemicals released by injured cells promote rapid release of neutrophils from red bone marrow? leukocytosis-inducing factors
What is leukocytosis and what is it a characteristic of? an increase of WBCs; characteristic of inflammation
In inflamed areas, endothelial cells sprout cell adhesion molecules (CAMs) called what? selectins
What do selectins provide for other CAMs on the surfaces of the neutrophils to bind? footholds (place to hold onto)
What is the phenomenon of complementary CAMs uniting, the neutrophils clinging to the inner walls of the capillaries and postcapillary venules? margination
What is a continued chemical signaling prompting the neutrophils to squeeze thru the capillary walls called? diapedesis or emigration
Inflammatory chemicals act as homing devices, or more precisely, ____? chemotactic agents, that attract the neutrophils and other WBCs to the site of the injury
What are the central actors in the final disposal of cell debris as an acute inflammation subsides? macrophages
What predominates at sites of prolonged, or chronic inflammation? macrophages
What is the ultimate goal of an inflammatory response? to clear the injured area of pathogens, dead tissue cells, and other debris so tissue can be repaired
What is a mixture of dead or dying neutrophils, broken down tissue cells, and living and dead pathogens called? yellow pus
What forms if the inflammatory mechanism fails to clear the area of debris, and the sac of pus becomes walled off by collagen fibers? an abscess
What is often necessary to do to abscesses before healing can occur? surgical draining
What is a tumorlike growth containing a central region of infected macrophages surrounded by uninfected macrophages and an outer fibrous capsule? infectious granulomas
What enhances the innate defenses by attacking microorganisms directly or by hindering their ability to reproduce? antimicrobial proteins
What are the most important antimicrobial proteins? interferons and complement proteins
How do viruses invade the body? invading tissue cells and taking over the cellular metabolic machinery needed to reproduce themselves
What do virus-infected cells do to try to protect nearby uninfected cells? secrete small proteins called interferons (IFNs), which stimulate synthesis of proteins in the healthy cells and interfere with viral replication by blocking protein synthesis and degrading viral RNA
Is IFN protection virus specific? No, so they can protect against a variety of viruses
What are IFNs? a family of related proteins produced by a variety of body cells, each having a slightly different physiological effect.
What type of interferon do lymphocyes secrete? gamma, or immune interferon
What do other leukocytes secrete? alpha interferon
What secretes beta interferon? fibroblasts
Interferon beta and alpha reduce what? inflammation
Interferons have an antiviral effect and also activate ________ and mobilize ____ cells. macrophages; NK
Because both macrophages and NK cells can act directly against malignant cells, the interferons play some anticancer role true
What is used to treat genital warts (caused by human papillomavirus) and hepatitis C (the most common and serious form of hepatitis)? IFN alpha
What IFN is used to treat patients with MS, a demyelinating disease? beta
What term refers to a group of at least 20 plasma proteins that normally circulate in the blood in an inactivate state? complement system or complement
Complement proteins include C1 thru C9, factors B, D, and P, plus several regulatory proteins True
What provides a major mechanism for destroying foreign substances in the body? complement
The activation of what unleashes chemical mediators that amplify virtually all aspects of the inflammatory process? complement
What is an effect of complement on bacteria? certain bacteria and other cell types are killed by cell lysis
Is complement a nonspecific or specific defensive mechanism? nonspecific, but it enhances the effectiveness of both innate and adaptive defenses
In what 2 ways can complement be activated? classical pathway alternative pathway
Which complement activation method involves antibodies that the adaptive immune system produces to fight off foreign invaders? classical pathway
What is the step called complement fixation in the classical pathway complement activation method? the binding of antibodies to the invading organisms and the subsequent binding of C1 to the microorganism-antibody complexes
When is the alternative pathway triggered? When factors B, D, and P interact with polysaccharide molecules present on the surface of certain microorganisms
What is it called when C3b binds to the target cell's surface triggering the insertion of a group of complement proteins into the cell's membrane? MAC (membrane attack complex)
What is produced by the liver in response to inflammatory molecules, is used as a clinical marker to assess for the presence of an acute infection or an inflammatory condition and its response to treatment? C-reactive protein (CRP)
Fever is a stystemic response to the invasion of microorganisms True
What prompts a fever? chemical called pyrogens, secreted by leukocytes and macrophages exposed to foreign substance in the body
How does fever help to keep bacteria from multiplying? During a fever, the liver and spleen make iron and zinc less available, needed in large amounts for bacterial multiplication; also increases the metabolic rate of tissue cells in general, speeding up repair processes
What is the adaptive immune system? the body's built-in specific defensive system that stalks and eliminates with nearly equal precision almost any pathogen
What are 3 important aspects of the adaptive immune response? 1) specificity - recognizes particular pathogens that initiate the immune response 2) systemic - immunity is not restricted to the initial infection site 3) memory - recognizes and mounts even stronger attacks on previously encountered pathogens
What is provided by B cells present in the body's 'humors', or fluids (blood, lymph)? humoral immunity or antibody-mediated immunity
What is it called when lymphocytes themselves rather than antibodies defend the body? cellular immunity or cell-mediated immunity, because the protective factor is living cells
What kind of targets do cellular immunity have? cellular targets-virus infected or parasite-infected tissue cells, cancer cells, and cells of foreign grafts
Lymphocytes act against cellular targets directly, by killing the foreign cells, or indirectly, by releasing chemical mediators that enhance inflammatory response or activate other lymphocytes or macrophages true
Substances that can mobilize the immune system and provoke an immune response are called what? antigens
Because antigens are large, complex molecules not normally present in the body, our immune system considers them what? intruders, or nonself
What 2 important functions do 'complete antigens' serve? 1) immunogenicity, the ability to stimulate proliferation of specific lymphocytes and antibodies 2) reactivity, the ability to react with the activated lymphocytes and the antibodies released by immunogenic reactions
Of foreign proteins, many large polysaccharides, and some lipids and nucleic acids, which of these complete antigens are the strongest? proteins
Substances whose surfaces bear many different foreign macromolecules, ie pollen grains and microorganisms, such as bacteria, fungi, and virus particles,are all considered what? immunogenic
Are small molecules, such as peptides, nucleotides, and many hormones, generally consider immunogenic? Not unless they link up with the body's own proteins and are recognized as foreign and an attack is mounted by the adaptive immune system
What is a troublesome small molecule that links up with the body's own proteins? hapten, or incomplete antigen
Haptens have reactivity but not immunogenicity unless attached to what? protein carriers
Chemicals that act as haptens are found in what? poison ivy, animal dander, detergents, cosmetics, certain drugs esp penicillin, and some household and industrial products
The ability of a molecule to act as an antigen depends on what 2 things? its size and its complexity
Only certain parts of an entire antigen are immunogenic. What are these parts called? antigenic determinants
Why do plastics have little or no immunogenicity and so are used to make artificial implants and wont be rejected by the body? Because they have many identical, regularly repeating units making them not chemically complex
Our own body's antigens are not foreign or antigenic, so why are they strongly antigenic to other individuals? their cells are programmed for self-antigens
What are the 2 major groups of major histocompataility complexes (MHC) proteins? Class I MHC proteins - found on most body cells Class II MHC proteins - found only on cells that act in immune response
What are the 3 crucial cell types of the adaptive immune system that have 2 distinct populations of lymphocytes, and antigen-presenting cells (APCs)? B lymphocytes or B cells - oversee humoral immunity T lymphocytes or T cells - non antibody producing lymphocytes that constitute the cell-mediated arm of adaptive immunity
What is the ability of a lymphocyte to recognize its one specific antigen by binding to it called? immunocompetence
What is the lymphocytes ability to be relative unresponsive to self-antigens so that it doesnt attack the body called? self-tolerance
T cells undergo a 2-3 day maturation process to become immunocompetent and self-tolerant where? in the thymus
B cells become immunocompetent and self-tolerant where? in the bone marrow
When B or T cells become immunocompetent, they display a unique type of receptor on their surface that enable the lymphocyte to do what? recognize and bind to a specific antigen
The receptors on B cells are membrane-bound what? antibodies
The receptors on T cells are products of what? the same gene superfamily
What 2 things must a T cell be able to do? to bind MHC molecules and the T cell must not react strongly to self-antigens normally in the body
What is an MHC restriction process that identifies T cells whose receptors are capable of recognizing self-MHC molecules, thus producing an army of self-MHC-restricted T cells? positive selection, which occurs in the thymic cortex
What happens to T cells that react vigorously to self antigens bound to self-MHC? they are eliminated by apoptosis (programmed cell death) and is called negative selection
Where does negative selection occur? in the inner edge of the thymic cortex
What does negative selection ensure? that T cells don't attack the body's own cells and cause autoimmune disorders
About what percentage of T cells make it through 'training'? 2%
Two methods used in self-reactive B cells are? apoptosis, or receptor editing, which is changing their self-reactive antigen receptor
Self-reactive B cells that do leave the bone marrow are inactivated, a phenomenon called what? anergy
What are immunocompetent T and B cells that have not yet been exposed to antigen? naive
Where are naive T and B cells exported to? lymph nodes, spleen and other secondary lymphoid organs, where encounters with antigens occur
What must occur before naive lymphocytes can complete their differentiation into fully functional T and B cells? they must bind with recognized antigens
Is it our genes or our antigens that determine what specific foreign substances our immune system will be able to recognize and resist? genes
What is the process of shuffling and combining gene segments in different ways by each lymphocyte as it become immunocompetent? somatic recombination
What is the major role of antigen-presenting cells (APCs) in immunity? engulf antigens and then present their fragments on their own surfaces where they can be recognized by T cells, called presenting antigens to the cells that will deal with the antigens
What are the major types of cells acting as APCs? dendritic cells (found in connective tissues and in the epidermis, aka Langerhans' cells) macrophages, and B lymphocytes
Lymphocytes, esp T cells, account for what % of bloodborne lymphocytes? 65% - 85%, circulate continuously thru the body
This process occurs when a B-cell is presented with an antigen (called the antigen challenge). clonal selection.
Lymphocytes and APCs in the tonsils act primarily against microorganisms that invade what? the oral and nasal cavities
The spleen acts as a filter to trap what? bloodborne antigens
Why are dendritic cells the most effective antigen presenters? its their only job and they have long veil-like extensions
Dendritic cells are a key link between which immunities? innate and adaptive
The adaptive immune system uses lymphocytes, APCs, and specific molecules to id and destroy all substances-living and non-living- that are not recognized as self true
The first encounter between an immunocompetent but naive lymphocyte and an invading antigen, usually takes place in the spleen or lymph node or any lymphoid tissue is called what? the antigen challenge
IF the lymphocyte is a B cell, the challenging antigen provokes what? the humoral immune response, where antibodies are produced against the challenger
When is an immunocompetent but naive B lymphocyte activated (stimulated to complete its differentiation)? when antigens bind to its surface receptors and cross-link adjacent receptors together
What are the events that stimulate the B cell to grow and then multiply rapidly to form an army of identical cells and bearing the same antigen-specific receptors called? clonal selection
What do most cells of the clone become? plasma cells, the antibody-secreting effector cells of the humoral response
Plasma cells develop the elaborate internal machinery needed to secrete antibodies at the rate of about ___ molecules per second 2000
Plasma cells secrete antibodies at the rate of 2000 molecules per second for 4-5 days then die true
Clone cells that don't differentiate into plasma cells become long-lived what? memory cells
Clonal selection and differentiation of B cells constitute what? the primary immune response, occurs on 1st exposure to particular antigen
What is the lag period of the primary response after the antigen challenge? 3-6 days
What is the response called when someone is exposed to an antigen after the first exposure? secondary immune response
Why are secondary immune responses faster, more prolonged, and more effective? because immune system has already been primed to the antigen and memory cells are already in place and provide immunological memory
What is a titer? concentration
When B cells encounter antigens and produce antibodies against them, what is being exhibited? Active humoral immunity
When is active immunity naturally acquired? when you get a bacterial or viral infection, during which time you may develop symptoms of the disease
What are the 2 types of active humoral immunity? natural and passive
What is passive humoral immunity? antibodies are harvested from serum of an immune donor
What are the 2 types of passive humoral immunity? naturally, ie a baby receives all the antigens to which the mother has been exposed; and artificially, ie a serum such as gamma globulin, administered after exposure to hepatitis
Why are other immune sera used to treat poisonous snake bites (antivenom), botulism, rabies, and tetanus (antitoxin)? because these diseases would kill a person before active immunity could be established
Antibodies are also called what and constitute the gamma globulin part of blood proteins? immunoglogbulins (Igs)
How many amino acids are contained in the 2 heavy chains of the antibody structure? 400 in each chain
What is the molecule called that is formed by the antibodies four chains? antibody monomer
What do the V regions of the heavy and light chains in each arm of the monomer combine to form? an antigen binding site shaped to 'fit' a specific antigenic determinant
What part of the antibody monomer determines the antibody class and serves common functions in all antibodies and what are they called? the C regions that form its stem; they are called the effector regions of the antibody
What do effector regions of the antibody dictate? 1) the cells and chemicals the antibody can bind to 2) how the antibody class functions in antigen elimination
How are the 5 major Ig classes designated? on the basis of the C regions in their heavy chains
Which 3 Igs have the same basic Y-shaped structure and thus are monomers? IgD, IgG, and IgE
What is a dimer? two linked monomers
Which is the largest antibody? IgM - a pentamer constructed from 5 linked monomers
What is the biological role and location of IgM? it is the first antibody class released to the blood by plasma cells
What is the biological role and location of IgG? it is the most abundant antibody in plasma and the only Ig class that crosses the placental barrier
What is the biological role and location of IgA? it is found primarily in mucus and other secretions that bathe body surfaces and plays a major role in preventing pathogens from gaining entry into the body
What is the biological role and location of IgD? it is always bound to a B cell surface, so acts as a B cell receptor
What is the biological role and location of IgE? it is found in minute quantities in some allergies
What is the antibodies role in destroying antigens? They inactivate them and tag them for destruction
What are the defense mechanisms used by antibodies and which 2 are most important? neutralization, agglutination, precipitation, and complement fixation (1st 2 are most important)
What is the simplest effector mechanism and occurs when antibodies block specific sites on viruses or bacterial exotoxins? neutralization
What occurs when cell-bound antigens are cross-linked? agglutination (clumping)of the foreign cells
What is the name for soluble molecules are cross-linked into large complexes that settle out of solution making the antigen molecules more easily captures and engulfed by phagocytes? precipitation
What is the chief antibody ammunition used against cellular antigens, such as bacteria or mismatched red blood cells? complement fixation and activation
Easy way to remember how antibodies work: PLAN - Precipitation; lysis (by complement); agglutination; neutralization
What is a commercially prepared antibody used in research, clinical testing, and treatment? monoclonal antibodies
How are monoclonal antibodies made? by fusing tumor cells and B lymphocytes resulting in a cell hybrid, called hybridomas
What are some things monoclonal antibodies are used to diagnose? pregnancy, certain stds, some cancer, hepatitis and rabies
What diseases are monoclonal antibodies being used to treat? leukemia and lymphomas, cancers present in circulation
What serves as 'guided missiles' to deliver anticancer drugs only to cancerous tissue? monoclonal antibodies
Can antibodies protect against viruses and tuberculosis? No, only pathogens
What 2 structurally related cell differentiation glycoproteins that id the effector T cells? CD4 or CD8
What are the 2 major types of T cells and what do they do? CD4 cells; primarily helper T cells (TH) CD8 cells; cytotoxic T cells (Tc), which destroy any cells that harbor anything foreign
When is the only time antibodies invade solid tissues? when a lesion is present
Class I MHC proteins are displayed by virtually all body cells except? red blood cells
What are the 2 types of MHC proteins important to T cell activation? Class I MHC proteins and class II MHC proteins
Where are class I and II MHC protein synthesized? at the endoplasmic reticulum
What are the transport proteins called that transfer class I MHC proteins into the ER from the cytosol? TAPs (Transporter associated with Antigen Processing)
What are endogenous antigens? foreign proteins synthesized in a body cell
What are 2 examples of endogenous antigens? viral proteins produced by virus-infected cells and alien (mutated) proteins made by a body cell that has become cancerous
What is the important role of class I MHC proteins in the immune response? They provide the means for signaling to cytotoxic T cells that infectious microorganisms are hiding in body cells
Where are class II MHC proteins typically found? on surfaces of cells that present antigens to helper T cells: dendritic cells, macrophages, and B cells
What is an invariant chain? a protein bound by class II MHC molecule while still in the ER
How many polypeptide chains does a T cell antigen receptor (TCR) have? 2
What is the constraint of the helper and cytotoxic T cells called, that helps the class of MHC protein deliver the activation signal? the MHC restriction
What type of antigens do Helpter T cells (CD4) bind to? antigens linked to class II MHC proteins, usually found on APC surfaces
How are cytotoxic T cells (CD8) activated? by antigen fragments complexed with class I MHC proteins on surfaces of APCs
What must a T cell do before it can proliferate and form a clone? it must recognize one or more co-stimulatory signals
How is active natural immunity acquired? infection; contact with a pathogen
How is passive natural immunity acquired? antibodies pass from mother to fetus via placenta; or to infant in her milk
How is active artificial immunity acquired? via a vaccine; dead or attenuated pathogens
How is passive artificial immunity acquired? injection of immune serum (gamma globulin)
What is the basic antibody structure? (Based on IgG) 4 polypeptide chains (2 light, 2 heavy) joined by disulfide bonds
What are 2 examples of cells called antigen-presenting cells (APCs)? Macrophages and phagocytes
What engulf antigens and place their fragments on the surface of their cells to "flag" the T-cells that their defensive actions are needed by the body Macrophages and phagocytes
What is the group of mediators that influence cell development, differentiation, and responses in the immune system and are chemical messengers involved in cellular immunity? cytokines
What are 2 types of cytokines? interferons and interleukens
What releases interleukin 1? macrophages
What does interleukin 1 (IL-1)stimulate? T cells to liberate interleukin 2 (IL-2) and to synthesize more IL-2 receptors
What is IL-2? a key growth factor that sets up a positive feedback cycle that encourages activated T cells to divide even more rapidly
How is IL-2 used therapeutically? to treat melanoma and kidney cancers
What is required for full activation of most B and T cells, activate macrophages, and release essential cytokines? Helper T cells
How are immunocompetent helper (Th) and cytotoxic (Tc) T cells activated? by binding to an antigen-containing MHC protein displayed on the surface of an antigen presenting cell (APC)
What is also essential to activate Th and Tc T cells? a co-stimulatory signal
What do cytotoxic T cells do? directly attack and kill infected cells and cancer cells
Regulatory T cells help to maintain tolerance where? in the periphery
What is released by Th cells and mobilized lymphocytes and macrophages and attracts other types of white blood cells to the area and amplified innate defenses? Cytokines
What do cytotoxic T cells attack? mostly virus-infected cells, and tissues infected by bacteria o parasites, cancer cells and foreign cells introduced by blood transfusion or organ transplant
What are Tc cells often called bc of their ability to kill target cells by causing their lysis? cytolytic T cells
What chemicals are released from the T cell's granules once cytotoxic T cells recognize a target? perforin and granzymes
What part of the target cell do the perforins insert themselves into? the plasma membrane
What is the outcome when cytotoxic cells bind to a specific membrane receptor (a Fas receptor) on the target cell? stimulates the target cell to undergo apoptosis
What do tumor necrosis factor beta (TFN-B) and gamma interferon activate and enhance? macrophages and indirectly enhance the killing process
What is the process when natural killer cells (NK) and Tc lymphocytes roam the body, adhering to and crawling over surfaces of other cells, and examine them for markers they might recognize? immune surveillance
Why are regulatory T cells (Treg) important in preventing autoimmune reactions? because they suppress self-reactive lymphocytes in the periphery
Where are gamma delta T cells found mostly? in the intestinal epithelium
what makes Gamma delta T cells similar to NK cells than other T cell types? they have a different type of T cell receptor and recognize markers expressed by stressed or damaged cells and their large granular appearance
IMPORTANT!!!! What would happen if there were no helper T cells? There would be no adaptive immune response because the helper cells direct or help complete the activation of all other immune cells
What disease is evident of the importance of helper T cells? AIDS
What are autografts? tissue grafts from one body site to another in the same person
What are isografts? grafts from one patient to another that is genetically identical (identical twins)
What are allografts? grafts transplanted from individuals that are not genetically identical but are from the same species
What are xenografts? grafts taken from one species to another
Which are the most successful organ transplants? Autografts and isografts; always successful with an enough blood and no infection, bc the MHC-encoded proteins are identical
What is the most common and the most problematic graft type? allograft, with organ usually from a living human donor, (kidney, live, bone marrow) or one who has just died (heart or lung)
What immunosuppressive therapy is given after allograft surgery? corticosteroid drugs to suppress inflammation; antiproliferative drugs immunosuppressant drugs
What is the most common cause of death in transplant patients and why? bacterial and viral infection; because the immunosuppressive therapy leaves the patient's immune system weakened
What is any congenital or aacquired condition that causes immune cells, phagocytes, or complement to behave abnormally? immunodeficiency
What are the most devastating congenital conditions called? severe combined immunodeficiency (SCID) syndromes
What does SCID proudce? a marked deficit of B and T cells
What is cancer of the B cells called? Hodgkins disease, an acquired immunodeficiency
Created by: svking01