Chapter 15

What are the two mechanisms of antibody diversity?

"1] antigen-independent genetic recombination in the bone marrow,different combinations of light and heavy chains

Describe Interleukin-5 (IL-5)

Induces activation of cytotoxic T cells; promotes eosinophil differentiation and serves as chemokine for eosinophils

Describe B cells (B lympocytes) development

Lymphocytes that come directly from bone marrow to seed other organs (not the thymus) are called B lymphocytes.

Describe IgM antibodies

Responsible for allergic symptoms in immediate hypersensitivity reactions

Describe fixed phagocytes

The Kupffer cells in the liver, as well as phagocytic cells in the spleen and lymph nodes, are fixed phagocytes which are cell that are immobile ("fixed") in the walls of the sinusoids within these organs.

Describe adaptive immunity

The acquired ability to defend against specific pathogens after exposure to these pathogens, this is mediated by antigens and antibodies

Describe what the lymphoid organs filters

The spleen filters blood for pathogens, other organs filter lymph for pathogens.

Describe adjuvants

molecules that boost immune response when delivered with the vaccine antigens; found to be PAMPs

Describe plasma cells

protein factories that produce about 2,000 antibody proteins per second.

How many antibodies is estimated that an individual has?

100 million trillion (10^20), There should be an antibody for every antigen you might encounter.

Describe delayed hypersensitivity

Abnormal T cell response that produces symptoms 24−72 hours after exposure. Symptoms are caused by secretion of lymphokines, not histamine, so taking antihistamines has little effect. Example: contact dermatitis caused by poison oak, ivy, or sumac

Describe immunological surveillance

According to this concept, tumor cells frequently appear in the body but are normally recognized and destroyed by the immune system before they can cause cancer.

Describe the primary response of the active immunity

After infection, it takes 5−10 days before antibodies are detected in the blood. The person will get sick.

Describe the stem cells that lymphocytes develop from

Derived from stem cells in the bone marrow. These stem cells seed the thymus, spleen, and lymph nodes.

Describe the function of dendritic cells

Engulf protein antigens, partially digest them, and display polypeptide fragments on their surface for T cell to "see". Associated with histocompatibility antigens, secrete cytokines to attract T lymphocytes in secondary lymphoid organs. Once activated, the T cells divide for form effector T cells and memory T cells

Describe the 3 major groups of phagocytic cells

(1) neutrophils; (2) the cells of the mononuclear phagocyte system, including monocytes in the blood and macrophages (derived from monocytes) in the connective tissues; and (3) organ-specific phagocytes in the liver, spleen, lymph nodes, lungs, and brain

Describe thrombocytopenia

This may occur when a drug such as aspirin combines with platelets, resulting in the destruction of platelets.

Describe how our DNA codes for antibodies

Three segments in the antigen- combining region of a heavy chain and two in a light chain are coded by different segments of DNA and can be combined in different ways to make an antibody molecule.

Describe how dead neutrophils contribute to inflammation

Through the action of proteases, the neutrophils liquify the surrounding tissues, this produces a viscous, protein rich fluid that combines with the dead neutrophils to create pus. The remains of the neutrophils are then phagocytosed by macrophages.

Describe Hashimoto's thyroiditis

Thyroglobulin protein that is normally trapped within the thyroid follicles can stimulate the production of autoantibodies and autoreactive

Describe the effect of stress on cancer

Tumors also grow faster in lab animals under stress. Stress induces the release of cortisone, which is known to suppress the immune system.

Describe tumors

Tumors are abnormal clonal cells that dedifferentiate to an embryonic state. Tumor growth and dedifferentiation reveal antigens that can stimulate the destruction of the cell (by cytotoxic T cells).

Describe marcrophage intereactions with T cells due to a virus

Virus phagocytosed by macrophages or dendritic cells. Viral foreign antigens moved to the surface of the presenter cell. Foreign antigen forms a complex with MHC-2 molecule. Macrophage secretes IL-1 to stimulate cell division and proliferation of T cells

Describe immune complex diseases

When large numbers of immune complexes are continuously formed, however, the inflammation may be prolonged.The dispersion of immune com- plexes to other sites can lead to widespread inflammation and organ damage.

Describe the process of diapedesis

When the WBC are activated by chemokines released by invading bacteria, the WBC goes through the stages of rolling, capture, adhesion and activation, and finally extravasation (diapedesis) through the blood vessel wall. The steps of extravasation require the binding of particular molecules on the white blood cell surface to receptor molecules on the surface of endothelial cells.

Describe the structure of the antibody

Y-shaped protein with 2 long, heavy (H) chains joined by 2 shorter, light (L) chains, The bottom (Fc) is constant across different antibodies, whereas the top (Fab) varies and allows antigen specificity.

Describe the symptoms of immediate hypersensitivity

allergic rhinitis (chronic runny or stuffy nose); conjunctivitis (red eyes); allergic asthma; atopic dermatitis (urticaria, or hives); and food allergies.

Describe antigenic determinant sites

also known as epitopes, these are the areas of the molecule that stimulates the production and combination with antibodies. Large molecules can have several antigenic determinant sites

Describe the alternative pathway of complement activation

also results in the conversion of C3 into C3a and C3b and converges with the classical pathway

Describe rheumatoid arthritis

an autoimmune disease associated with the abnormal production of one group of antibodies (of the IgM type) that attack other antibodies (of the IgG type). This contributes to an inflammation reaction of the joints characteristic of the disease.

Describe immune complex

antigen-antibody com- binations that are free rather than attached to bacterial or other cells. The formation of such complexes activates complement proteins and promotes inflammation. This inflammation is normally self-limiting because the immune complexes are removed by phagocytic cells.

Describe malignant tumors

are fast growing and spread to other parts of the body (metastasize).

Describe benign tumors

are slow growing and limited to specific areas of the body.

Describe sympathetic ophthalmia

autoantibodies developed against lens protein in a damaged eye may cause the destruction of a healthy eye

Describe the results of histamine release

blood flow to the infected area is increased because of vasodilation and increased capillary permeability. This helps to bring in more phagocytic cells to combat the infection, but the increased capillary permeability can also result in edema through leakage of plasma proteins into the surrounding tissue fluid.

Describe how tumors evade immunological surveillance

by suppressing immunity with secretions: 1] FAS ligand stimulates lymphocyte apoptosis. 2] TGFβ - transforming growth factor beta 3] IL-10

Describe how neutrophils and monocytes are attracted to the infection site.

chemotaxis, movement toward chemical attractants called chemokines released by the macrophages.

Describe immunological tolerance

continued recognition and tolerance of self-cells

Describe lymphokines

cytokines specific to lymphocytes, called interleukin. Many stimulate B cell or cytotoxic T cell activity.

Describe gamma interferon

helps fight infections and cancer, only particular lymphocytes and natural killer cells are able to produce gamma interferons

Describe alpha and beta interferon

inhibit viral replication and assembly, almost all cells in the body are capable of producing alpha and beta interferon

Describe NETS

neutrophil extracellular traps, released by neutrophils to trap pathogens, they are composed of extracellular fibers that trap invading pathogens.

Describe TH1

produces IL-2 and gamma interferon - activates killer T cells and stimulates NO production in macrophages

Describe TH2

produces IL-4, IL-5, IL-13 and others - stimulates B cells and humoral immunity, recruits eosinophils and induces IgE production

List the common autoimmune diseaes

rheumatoid arthritis, type 1 diabetes, multiple sclerosis, Grave's disease, pernicious anemia, thyroiditis, psoriasis, and lupus

Describe TH17

secretes IL-17 - fights infections in skin, lungs, and mucous membranes; stimulates neutrophils

Describe class switch recombination

switch in the constant regions of the heavy chains of the antibodies, so that the original IgM antibodies are converted into IgG, IgA, or IgE antibodies

Describe immunological competence

the ability to mount an immune response, develops during early postnatal life - being able to distinguish self-antigens from foreign antigens

Describe the 3 effects of complement fragments

1] Chemotaxis - attracting phagocytic cells. 2] Opsonization - phagocytes have receptors for C3b; forms a bridge between phagocyte and victim cell to facilitate phagocytosis. 3] stimulation of the release of histamine from mast cells and basophils by fragments C3a and C5a.

What are the 3 types of T lymphocytes (T cells)

1] Killer or cytotoxic T cells, 2] Helper T cells 3] Regulatory T cells

Describe the 3 ways vaccines are produced

1] Use a killed virus (Salk polio vaccine), 2] Use a live virus with attenuated virulence—i.e., the virus either cannot replicate or cannot infect target tissues Sabin polio vaccine, MMR), 3] Use a genetically engineered recombinant virus (hepatitis B)

What are the two pathways of complement activation?

1] classic pathway: complement dependent cytotoxcity, initiated by the binding of antibodies of the IgG and IgM subclasses to antigens on the invading cell's membrane. This is more rapid and efficient. 2] alternative pathway: initiated by the unique polysaccharides that coat bacterial cells.

List the six reasons for autoimmune disease

1]An antigen that does not normally circulate in the blood may become exposed to the immune system. 2]A self-antigen that is otherwise tolerated may be altered by combining with a foreign hapten. 3]Antibodies may be produced that are directed against other antibodies. Antibodies produced against foreign antigens may cross-react with self-antigens. 4]Antibodies produced against foreign antigens may cross-react with self-antigens. 5]Self-antigens, such as receptor proteins, may be presented to the helper T lymphocytes together with class-2 MHC molecules. 6]Autoimmune diseases may result when there is inadequate activity of regulatory (suppressor) T lymphocytes.

Describe examples of passive immunity

1]From mother to fetus, 2]From mother to child (in breast milk - colostrum), 3]Artificially via immunization (snake anti-venom)

Descsribe what are the causes the autoimmune attack

1]If mutations occur in lymphocytes (usually good and adds to what the body can defend against), 2]If cells in particular organs are never exposed to the immune system, 3]These lymphocytes are called autoreactive.

What are the immunological tolerance mechanism?

1]In clonal deletion, these lymphocytes that recognize self-antigens are destroyed (apoptosis). 2]In clonal anergy, these lymphocytes are prevented from becoming active. Regulatory T lymphocytes likely do this.

Describe 6 internal defense mechanisms of the innate immune system

1]Phagocytic cells: Ingest and destroy bacteria, cellular debris, denatured proteins, and toxins, 2]Interferons: Inhibit replication of viruses, 3]Complement proteins: Promote destruction of bacteria; enhance inflammatory response, 4]Endogenous pyrogen: Secreted by leukocytes and other cells; produces fever, 5]Natural killer (NK) cells: Destroy cells infected with viruses, tumor cells, and mismatched transplanted tissue cells, 6]Mast cells: Release histamine and other mediators of inflammation, and cytokines that promote adaptive immunity

Describe 4 external defense mechanisms of the innate immune system

1]Skin:Physical barrier to penetration by pathogens; secretions contain lysozyme (enzyme that destroys bacteria), 2]Digestive tract:High acidity of stomach; protection by normal bacterial population of colon, 3]Respiratory tract:Secretion of mucus; movement of mucus by cilia; alveolar macrophages, 4]Genitourinary tract: Acidity of urine; vaginal lactic acid

Describe what causes fever

A chemical called an endogenous pyrogen sets the body temperature higher which is produced as a cytokine by leukocytes

Describe the clonal selection theory

A person inherits lymphocytes specific to almost every pathogen, but there are few of each type. antigens do not induce lymphocytes to make the appropriate antibodies. Rather, antigens select lymphocytes (through interaction with surface receptors) that are already able to make antibodies against that antigen. When exposed to foreign antigens, immune cells respond by making many copies of themselves.

Describe allergies

Abnormal response to allergens (antigens) Also called hypersensitivity; two types: immediate and delayed hypersensitivity

Describe the T cells intereactions with B cells

Activated helper Ts promote humoral response of B cells by binding to foreign antigens and MHC-2s. This stimulates mitosis of B cells, conversion to plasma cells, and production of antibodies.

Describe the destruction of T cells after infection is cleared

Active T cells produce a surface receptor called FAS and later a protein called FAS ligand. Binding of FAS to FAS ligand induces apoptosis.

Describe the formation of monoclonal antibodies

Animals are injected with an antigen. A single B lymphocyte that makes the desired antibodies is extracted. The B cell is fused with a cancerous myeloma cell in vitro. The hybridoma produces many clones that produce antibodies specific for the antigen

Describe autoantibodies and autoreactive T cells

Antibodies made against self-antigens are called autoantibodies. Killer T cells that attack self-antigens are called autoreactive T cells.

Describe the cause of rheumatic fever and glomerulonephritis

Antibodies produced in response to antigens in this bacterium may cross- react with self-antigens in the heart and kidneys. The inflammation induced by such autoantibodies can produce heart damage (including the valve defects characteristic of rheumatic fever) and damage to the glomerular capillaries in the kidneys (glomerulonephritis).

Describe antigen-presenting cells

Antigen recognition proteins on T cell membranes cannot bind directly on antigens and require the help of antigen-presenting cells such as dendritic cells and macrophages to bind to antigens

Describe the events in a local inflammation

Antigens on the surface of bacterial cells (1) bind to antibodies, which coat the bacteria. This activates complement and (2) promotes phagocytosis by neutrophils and macrophages. Activation of complement also (3) stimulates mast cells to release histamine and other mediators of inflammation, including chemicals that promote capillary permeability and (4) extravasation (diapedesis) of leukocytes, which invade the inflamed site.

Describe interferons

Antiviral polypeptides produced by infected cells, 3 major categories: alpha, beta and gamma interferon

Describe the mechanism of fixed phagocytes

As blood flows through these wide capillaries of the liver and spleen, foreign chemicals and debris are removed by phagocytosis and chemically inactivated within the phagocytic cells. Invading pathogens are removed so blood is usually sterile after a few passes through the liver and spleen. Fixed phagocytes in lymph nodes similarly help remove foreign particles from the lymph.

Define opsonization

Attachment of these antibodies to antigens in the bacteria greatly amplifies the innate response by greater activation of complement, which directly destroys the bacteria and together with the antibodies promotes the phagocytic activity of neutrophils, macrophages, and monocytes

Descirbe B cells involvement in local inflammation

B lymphocytes are stimulated to produce antibodies against specific antigens that are part of the invading bacteria, allowing opsonization to occur

Describe the activation of B cells

B lymphocytes have antibodies on their surface that function as receptors for specific antigens. The interaction of antigens and antibodies on the surface stimulates cell division and the maturation of the B cell progeny into memory cells and plasma cells.

Explain how antibodies destory a pathogen

Binding of antibodies to antigens does not destroy the pathogen. This labels targets for attack by phagocytic cells and stimulates opsonization and the complement system

Describe the regulation of body temperature

Body temperature is regulated by the hypothalamus, which contains a thermoregulatory control center that coordinates skeletal muscle shivering and the activity of the sympathoadrenal system to maintain body temperature at about 37°C

Describe (Complement) C1-C9

C1 serves as a recognition protein. C2, C3, and C4 serve as activators. C5−C9: complement fixation -attack by attaching to a cell membrane and destroying it.

Describe what happens after C3b is formed

C3b converts C5 into C5a and C5b. C3a and C5a stimulate mast cells to release histamine to increase blood flow to the area. C5b and C6−C9 form the membrane attack complex

Describes the effect of age on cancer

Cancer risk increases with age. This may be due to aging mutated lymphocytes and thymus functions are reduced - causes a decrease in cell-mediated immune competence

Describe cancer

Cancers arise when the immune cells fail to stop the growth/spread of the tumors which results from altered expression of oncogenes, tumor suppressor genes, or genes that code for microRNA

Describe antigens

Cell surface molecules that stimulate the production of specific antibodies and combine with those antibodies. They allow the immune system to distinguish "self" from "nonself."

Describe the method of action of T cells

Cell-mediated destruction means the T cells must touch the target victim. T cells secrete perforins to create large pore in cell, and granzymes to trigger apoptosis in cell through the action of caspase enzymes

Describe the two types of immunological tolerance

Central - occurs in the thymus (T cells) and bone marrow (B cells), Peripheral - anywhere outside the thymus or bone marrow

Describe class 1 of MHC molecules

Class 1 is made by all cells except RBCs. Class 1 MHC molecules and foreign antigens are presented together to activate cytotoxic T cells. Because Killer T cells have CD8 for MHC-1

Describe class 2 of MHC molecules

Class 2 is made by antigen-presenting cells and B cells. Class 2 MHC molecules and foreign antigens are presented together to helper T lymphocytes. Helper T cells have CD4 for MHC-2

Describe immediate hypersensitivity

Dendritic cells stimulate TH2 helper T cells to secrete interleukin-4 and interleukin-13, which stimulate B and plasma cells to secrete IgE antibodies. These antibodies do not circulate in the blood but attach to mast cells and basophils. When re-exposed to the same allergen, these antibodies bind with it and stimulate the production of histamine, leukotrienes, and prostaglandin D, producing allergy symptoms.

Describe the response to endotoxins

Endotoxins from some bacteria stimulate leukocytes to produce cytokines which causes fever, induce sleepiness and a fall in plasma iron concentration (which limits bacterial activity).

Describe the tubules of the testis of the eye as a immunologically privileged site

First, the tight junctions between adjacent Sertoli cells form a barrier that normally prevents exposure of the immune system to the developing sperm. Second, the Sertoli cells produce FAS ligand, which triggers apoptosis of any T lymphocytes that may enter the area.

Describe the membrane attack complex

Fixed complement proteins C5 through C9 assemble in the plasma membrane of the victim cell as a membrane attack complex. This complex forms a large pore that punctures the membrane and thereby promotes the destruction of the cell through lysis by causing influx of water into the cell

Describe what occurs when foreign antigens are detected

Foreign antigens illicit an immune response. Antibodies bind to their specific antigens.

Describe IgE antibodies

Function as antigen receptors on lymphocyte surface prior to immunization; other functions unknown

Describe IgD antibodies

Function as antigen receptors on lymphocyte surface prior to immunization; secreted during primary response

Describe germinal centers in secondary lymphoid organs

Germinal centers develop to produce the clones following exposure to an antigen. develops from a B cell that has been stimulated by an antigen and activated by helper T cells. This B cell then undergoes extremely rapid mitotic cell division to become the founder of a germinal center that contains a clone of memory cells and plasma cells,which secrete antibodies for the secondary immune response.

Describe attenuation

Greatly reducing virulence of a virus but not significantly chaning antigenicity, like in vaccines

Describe Killer T cells

Have surface molecules called CD8. Destroy body cells that harbor foreign antigens. Usually from a pathogen (virus or fungus), but can be due to a malignancy (cancer) or transplant cells

Describe helper T cells do once macrophages stimulate them

Helper T cells secrete macrophage colony-stimulating factor and gamma interferon, which promote macrophage activity. They also secrete interleukin-2, which makes the macrophage produce tumor necrosis factor (against cancer) and activates cytotoxic T cell activity/mitosis.

What is the benefit of T cell destruction

Helps maintain immunologically privileged sites - inner region of the eye and tubules of the testis - protects molecules that could be seen as foreign by the immune system

Describe somatic hypermutation

High rate of mutations of single base pairs in DNA in body cells

Describe degranulation

Histamine and heparin, together with protease enzymes are stored granules within the mast cells. During allergic reaction or as normal physiological response to pathogen, mast cells are stimulate to degranulate

Describe the action of histamine

Histamine binds to the H1 receptors in the smooth muscle of bronchioles to stimulate the bronchiolar constriction and produces vasodilation in blood vessels. Histamine increases capiallary permeability so that more leukocytes can enter the inflammed area.

Describe the classical pathway of complement activation

IgG and IgM activate C1, which splits C4 into two fragments, C4a and C4b. C4b binds to the cell membrane and becomes active, splitting C2 into C2a and C2b. C2a attaches to C4b and cleaves C3 into C3a and C3b.

What are the five classes of antibodies (immunoglobins)

IgG, IgA, IgM, IgD, and IgE

Describe how the innate immune system distinguishes between the body's own tissue cells and invading pathogens

Immune cells have pathogen recognition receptors on the surface, such as toll-like receptors that by recognizes molecules called pathogen-associated molecular patterns (PAMPs) that are unique to the invaders. These cells respond by secreting chemokines to recruit more immune cells or activate specific immune cells.

Describe the anterior chamber of the eye as a immunologically privileged site

Immunological privilege here is beneficial because any inflammation triggered by an immune response could interfere with the transparency required for vision or damage the neurological layers of the retina, which cannot regenerate. Mechanism include coating of the interior of the eye with FAS ligand, which promotes apoptosis of leukocytes, and the secretion of different cytokines, which inhibit inflammation through a variety of mechanisms.

Describe Interleukin-1 (IL-1)

Induces proliferation and activation of T lymphocytes

Describe Interleukin-2 (IL-2)

Induces proliferation of activated T lymphocytes

Describe the difference between innate (nonspecific) and adaptive (specific) immunity

Innate (nonspecific) immunity - inherited; Adaptive (specific) immunity - learned from exposure to specific pathogens; function of lymphocytes

Describe the complement system

Integrates innate and adaptive immune responses. Consists of proteins in the plasma that become activated when antibodies bind to antigens. Complement proteins promote phagocytosis, lysis of target cells, and inflammation.

Describe the secondary response of the active immunity

Later exposure to the same infection results in maximum antibody production in less than 2 hours. The person will likely never get sick.

Provide an example of toll-like receptor activation

Lipopolysaccharides (LPS) found on the membrane of gram negative bacteria stimulates dendritic cells and macrophages which secrete cytokines to recruit other immune system cells and promote innate immune response such as phagocytosis and fever

Describe the secondary lymphoid organs

Lymph nodes, spleen, tonsils, and Peyer's patches (in mucosa of intestines). Their function is to capture and present pathogens to macrophages and house lymphocytes. Lymphocytes migrate between lymphoid organs to sample blood and lymph.

Describe the function macrophages during inflammation

Macrophages ingest microorganisms and fragments of the extracellular matrix by phagocytosis; they also release nitric oxide, which aids in the destruction of bacteria. The numbers of macrophages are increased by the recruitment of monocytes, which adhere to extracellular matrix proteins and transform into macrophages.

Describe IgA antibodies

Main antibody type in external secretions, such as saliva and mother's milk. IgA antibodies also protect the mucosa of the intestine from both commensal bacteria

Describe IgG antibodies

Main form of antibodies in circulation: production increased after immunization; secreted during secondary response

Describe major histocompatibility complex (MHC)

Many versions of each gene are possible, so most people have different combinations. The closer two people are related, the closer the match between their histocompatibility antigens. An organ transplant requires an MHC match.

Describe mast cells

Mast cells degranulate and secrete heparin, histamine, prostaglandins, leukotrienes, cytokines, and TNF-α, which produce warmth, swelling, and pain (classic symptoms). They also recruit more leukocytes.

Describe what diseases results from self antigens presenting to T helper cells along with MHC-2 molecules

May occur after viral infection of cells and occurs in diabetes type I, Graves Disease

Describe what causes immune complex diseases

May result from infections from bacteria, viruses, or parasites like Hepatitis B results in free complexes that cause damage to arteries due to inflammation. Or may also result from complexes formed by self antigens and autoantibodies like in Rheumatoid arthritis and lupus

Describe the function of macrophages

Most of the time, macrophages operate separately from the immune system as they perform the simple service of clearing cellular debris, such as the remnants of cells that die normally from apoptosis. When they recognize pathogenic signals through the activation of their toll-like receptors, they become activated to secrete pro-inflammatory cytokines and recruit neutrophils and monocytes

Describe the mechanism of natural killer cells

Must be activated by pro-inflammatory cytokines from dendritic cells. Kill compromised cells in the same manner as cytotoxic T cells. Cytokines released by natural killer cells activate both innate and adaptive immune cells.

Describe how neutrophils and monocytes enter the infected tissue

Neutrophils and monocytes squeeze through gaps in post-capillary venule walls to enter tissue in a process called extravasation, or diapedesis. Neutrophils are the first to arrive at the site of an infection; monocytes arrive later and can be transformed into macrophages as the battle progresses.

Describe the role of neutrophils during inflammation

Neutrophils arrive early and release chemical signals that recurit other phagocytic cells. The neutrophils kill microorganisms through phagocytosis and through the action of proteases

Describe autoimmune diseases

those produced by failure of the immune system to recognize and tolerate self-antigens. This failure results in the activation of autoreactive T cells and the production of autoantibodies by B cells, causing inflam- mation and organ damage

Describe intiation of local inflammation

Occurs when bacteria enter a break in the skin. Initiated by nonspecific mechanisms of phagocytosis by toll-like receptors

Describe histocompatibility antigens

On surface of all body cells (except mature RBCs); also called human leukocyte antigens (HLAs)

Describe the origin of dendritic cells

Originate in the marrow and migrate to most tissues (especially where pathogens might enter body)

Describe passive immunity

Passing of antibodies from one individual to another; person does not make their own antibodies. Provides temporary protection:

Describe CD25 and FOXP3

People with a genetic deficiency in CD25 develop severe autoimmune disease and allergy, demonstrating the importance of CD25 and Treg function. Also, Treg lymphocytes have been distinguished by the activation of a gene known as FOXP3, which codes for a transcription factor that appears to be required for the development and maintenance of regulatory T lymphocytes.

Describe Carcinoembryonic antigen tests

useful in the diagnosis of colon cancer and tests for alpha-fetoprotein (normally produced only by the fetal liver) help in the diagnosis of liver cancer.

Describe the function of pus

Pus may be beneficial by creating pressure that closes lymphatic and blood capillaries, blocking the spread of bacteria away from the battle site.

Describe memory cells

visually indistinguishable from the original cell and are important in active immunity, used in a later infection by the same pathogen.

Describe the symptoms of local inflammation

Redness and warmth due to histamine stimulated vasodilation, swelling due to vasodilation, pain due to release of PGE2 and pus due phagocytosis

Describe natural killer cells

Related to T lymphocytes but part of innate immunity without the ability to recognize specific antigens. Can recognize malignant cells and cells infected with a virus.

Describe haptens

Smaller, nonantigenic molecules that can become antigens when bound to other proteins. These are useful for creating antigens for research and diagnosis.

Describe how tumor antigens arise

Some tumor antigens are due to dedifferentiated embryonic antigens not recognized by the immune system. Some arise due to mutations from carcinogens. Others are viral antigens from the virus that caused the tumor (human papillomavirus).

Describe the mechanism of vaccines

Stimulate a primary response and active immunity without making the person sick.

Describe Interleukin-6 (IL-6)

Stimulates proliferation and activation of T and B lymphocytes

Describe Granulocyte/ monocyte-macrophage colony-stimulating factor (GM-CSF)

Stimulates proliferation and differentiation of neutrophils, eosinophils, monocytes, and macrophages

Describe Interleukin-4 (IL-4)

Stimulates proliferation of activated B cells; promotes production of IgE antibodies; increases activity of cytotoxic T cells

Describe Interleukin-3 (IL-3)

Stimulates proliferation of bone marrow stem cells and mast cells

Describe Helper T cells

Surface molecule is CD4. Improve ability of B lymphocytes to become plasma cells and enhance ability of cytotoxic T cells to kill targets by secretion of lymphokines

Describe Regulatory T cells

Surface molecules CD4 and CD25. Previously called suppressor T lymphocytes. Inhibit response of B lymphocytes and killer T lymphocytes

Describe immunoassays

Tests that use specific antibodies to identify specific antigens. Binding causes agglutination, which can be seen. Used to determine blood type and detect pregnancy

Describe primary lymphoid organs

The bone marrow and thymus are considered primary lymphoid organs

Describe how macrophages deal with cells that die through apoptosis

The cells signal macrophages to attack by displaying a phosphatidylserine on their surface that normally is found only on the inner layer of the plasma membrane. The phosphatidylserine provides an "eat me" signal to macrophages. Note that inflammatory processes are suppressed when macrophages eat apoptotic body cells.

Describe the order of phagocytic cell arrival to infection site

The first to arrive are the neutrophils, followed by monocytes (which can change into macrophages) and T lymphocytes

Describe the immune system

The immune system includes all of the structures and processes that provide a defense against potential pathogens (disease-causing agents). These defenses can be grouped in two categories: innate (or nonspecific) immunity and adaptive (or specific) immunity.

Describe how necrosis can intiate innate immune response

The immune system is exposed to DAMPs - danger associated molecular patterns from the necrotic tissues. In cells that undergo apoptosis through programmed cell death do not express DAMPs so they do not invoke inflammation.

Describe the process of phagocytosis

The pathogen becomes engulfed by pseudopods. If the pseudopods fuse to form a complete food vacuole, lysosomal enzymes are restricted to the organelle formed by the lysosome and food vacuole. If the lysosome fuses with the vacuole before fusion of the pseudopods is complete, lysosomal enzymes are also released into the infected area of tissue.

Describe T cells (T lymphocytes) develoopment

The thymus is the site of new T lymphocytes through late childhood. It degenerates in adulthood, and new T lymphocytes are made through mitosis in secondary lymphoid organs.

Describe immunotherapy for cancer

Therapeutic monoclonal antibodies, interferons, and interleukin-2 have been used to treat cancer. None of these "cure" cancer, but they do help some people. Other cytokines are currently being tested against cancer.

Describe the functon of the granule proteins relased by neutrophils

They are recongized by monocytes rolling along the endothelium of capillaries. These promote monocytes to infection site, where they can adhere to extracelluar matrix proteins and transform into macrophages.

Describe the type of immunity of T cells provides

They attack by cell-mediated immunity. They must be in close proximity to the victim cell in order to destroy it. T lymphocytes do not produce antibodies. T lymphocytes attack host cells that have become infected with a virus or fungus, transplanted human cells, and cancer cells.

Describe the type of immunity B cells provides

They attack by humoral immunity or antibody-mediated immunity. They secrete antibodies into blood and lymph so can be far from the victim. They combat bacterial and some viral infections.