Chapter 43: The Immune Chapter 43: The Immune SystemSystem

DiseaseDiseaseA departure from healthA departure from healthTypes:Types:

Deficiency diseasesDeficiency diseasesGenetic diseasesGenetic diseasesCommunicable diseasesCommunicable diseases

Contagious diseaseContagious diseaseInfectious diseaseInfectious disease

Host provides metabolic needs of pathogen or Host provides metabolic needs of pathogen or parasiteparasite

Infectious diseaseInfectious disease TransmissionTransmission

ContactContact Droplet infectionDroplet infection VectorVector Common vehicle transmissionCommon vehicle transmission

TypesTypes Sporadic diseaseSporadic disease Endemic diseaseEndemic disease Epidemic diseaseEpidemic disease Pandemic diseasePandemic disease

Adaptations of pathogen to Adaptations of pathogen to resist host defenseresist host defense

Cell wallCell wall Contain proteins to resist host &/or Contain proteins to resist host &/or

antibioticsantibiotics Sticky capsuleSticky capsule

Counters phagocytosis; increases Counters phagocytosis; increases virulence of pathogenvirulence of pathogen

Production of enzymes or metabolic Production of enzymes or metabolic toxinstoxins

Manipulates host cell’s metabolic Manipulates host cell’s metabolic structurestructure virusesviruses

Adaptations of the Human Adaptations of the Human BodyBody

11stst line of defense line of defense Physical shieldPhysical shield

Skin, mucus, ciliated cells, tears, urine flow, Skin, mucus, ciliated cells, tears, urine flow, coughing, sneezing, ear waxcoughing, sneezing, ear wax

Chemical shieldChemical shield Stomach acids kill bateriaStomach acids kill bateria Enzymes (lysozyme) in tears etc. Enzymes (lysozyme) in tears etc. Skin acidsSkin acids

22ndnd line: inflammatory response line: inflammatory response Increased blood flowIncreased blood flow

Promotes healingPromotes healing Swelling insulates tissuesSwelling insulates tissues

Macrophages, neutrophils, Eosinophils, Macrophages, neutrophils, Eosinophils, & Dendritic cells& Dendritic cells

Phagocytic activity to engulf pathogenPhagocytic activity to engulf pathogen Macrophages:Macrophages:

Develop from monocytesDevelop from monocytes Migrate through the body or reside permanently Migrate through the body or reside permanently

in some organs (i.e. spleen)in some organs (i.e. spleen) Neutrophils:Neutrophils:

Enter infected tissue to engulf microbesEnter infected tissue to engulf microbes Self destruct Self destruct

Eosinophils:Eosinophils: Position against multi-cellular parasite & release Position against multi-cellular parasite & release

enzymes to destroyenzymes to destroy Dendritic cells:Dendritic cells:

Can act like macrophages but are usually Can act like macrophages but are usually involved in acquired immunityinvolved in acquired immunity

Injured, circulating basophils release Injured, circulating basophils release histamines & prostaglandinshistamines & prostaglandins

Promotes vasodilationPromotes vasodilation Capillaries become “leaky”Capillaries become “leaky” Attracts phagocytic cells Attracts phagocytic cells

Neutrophil engulfs bacteriaNeutrophil engulfs bacteria macrophage engulfs macrophage engulfs neutrophilneutrophil

Infected cells release interferonInfected cells release interferon Stimulate adjacent cells to produce proteins Stimulate adjacent cells to produce proteins

that prevent viral replicationthat prevent viral replication Activates phagocytesActivates phagocytes

33rdrd line: Immune response line: Immune response Production of LymphocytesProduction of Lymphocytes

Circulate in blood & lymphCirculate in blood & lymph Concentrated in spleen, lymph nodes, & Concentrated in spleen, lymph nodes, &

lymphoid tissuelymphoid tissue Each lymphocyte is specific to a particular Each lymphocyte is specific to a particular

foreign antigenforeign antigen Originate in stem cells of bone marrowOriginate in stem cells of bone marrow Types:Types:

B cellsB cells Mature in bone marrowMature in bone marrow

T cellsT cells Mature in thymus glandMature in thymus gland

Maturing B cells & T cells tested for self-Maturing B cells & T cells tested for self-reactivity & destroyed if self reactivereactivity & destroyed if self reactive

Production of specific antibodies by Production of specific antibodies by lymphocyteslymphocytes AntitoxinsAntitoxins

Neutralize bacterial toxinsNeutralize bacterial toxins AgglutininsAgglutinins

Clumping of bacteriaClumping of bacteria OpsoninsOpsonins

Stimulate phagocytosis of clumped bacteriaStimulate phagocytosis of clumped bacteria LysinsLysins

Dissolve cell walls of bacteriaDissolve cell walls of bacteria PrecipitinsPrecipitins

Coagulation chemicals of bacteriaCoagulation chemicals of bacteria

Immunoglobins (antibodies)Immunoglobins (antibodies) Specific antigen binding immunoglobulinsSpecific antigen binding immunoglobulins Generated by B cellsGenerated by B cells TypesTypes

IgMIgM First antibodies to arrive at infection siteFirst antibodies to arrive at infection site

IgCIgC Most abundant antibodies in blood & lymphMost abundant antibodies in blood & lymph

IgAIgA Antibodies found in body secretions (saliva, sweat)Antibodies found in body secretions (saliva, sweat)

IgEIgE Trigger release of histamines & other chemicals by Trigger release of histamines & other chemicals by

mast cells & basophils to cause allergic reactionsmast cells & basophils to cause allergic reactions IgDIgD

On naïve B cells (not yet exposed to foreign On naïve B cells (not yet exposed to foreign antigen)antigen)

Receives antigen that leads to clonal selectionReceives antigen that leads to clonal selection

Self/non-selfSelf/non-self Immune system must be able to Immune system must be able to

distinguish foreign from non-foreign distinguish foreign from non-foreign proteinsproteins

Major histocompatability complex (MHC)Major histocompatability complex (MHC) Group of glycoproteins embedded in cell Group of glycoproteins embedded in cell

membranemembrane Two major classes of MHCTwo major classes of MHC

Class I MHCClass I MHC Bind to cytotoxic T cellsBind to cytotoxic T cells

Class II MHCClass II MHC Known as antigen presenting cellsKnown as antigen presenting cells Bind to specialized cells (macrophages, B cells) & Bind to specialized cells (macrophages, B cells) &

activate T cellsactivate T cells

Action of lymphocytesAction of lymphocytes Humoral ResponseHumoral Response

B cellsB cells Enter blood & produce specific antibodies to counter Enter blood & produce specific antibodies to counter

specific antigensspecific antigens Antigen-antibody complexes are formedAntigen-antibody complexes are formed

Helper T cellsHelper T cells Secrete interleukinsSecrete interleukins

Stimulate clonin of B cells to memory cellsStimulate clonin of B cells to memory cells B cells into memory cells (M cells)B cells into memory cells (M cells)

Long lived cellsLong lived cells Recognize specific antigenRecognize specific antigen Basis of active immunityBasis of active immunity

Plasma cells (P cells)Plasma cells (P cells) Short lived cellsShort lived cells Produce additional antibodies with initial exposure to Produce additional antibodies with initial exposure to

antigenantigen Antibodies draw phagocytic cells in to destroyAntibodies draw phagocytic cells in to destroy

Cell mediated responseCell mediated response Cytotoxic T cellsCytotoxic T cells

Stored in thymus gland prior to moving into Stored in thymus gland prior to moving into bloodblood

Activated when CD8 receptors recognize Activated when CD8 receptors recognize antigen on Class I MHC; helper T cell antigen on Class I MHC; helper T cell releases cytokines to promote activationreleases cytokines to promote activation

Do not produce antibodiesDo not produce antibodies Attack & kill antigen-bearing cellsAttack & kill antigen-bearing cells

Secrete proteins that destroy infected cellsSecrete proteins that destroy infected cells Stimulate the production of B cellsStimulate the production of B cells

Dispose of infected cellsDispose of infected cells Suppress B cell reproduction when Suppress B cell reproduction when

infection has been suppressedinfection has been suppressed Secrete interferon which defends Secrete interferon which defends

healthy cells from virushealthy cells from virus

Primary vs. Secondary immune Primary vs. Secondary immune responseresponse

Primary immune responsePrimary immune response First exposure or vaccination to antigenFirst exposure or vaccination to antigen Results in formation a specific antibody to Results in formation a specific antibody to

inactivate an antigen inactivate an antigen Requires time to occurRequires time to occur

Secondary immune responseSecondary immune response Rapid reproduction of specific antibodies to Rapid reproduction of specific antibodies to

inactivate & destroy antigen (immediate)inactivate & destroy antigen (immediate)

Types of DefenseTypes of Defense Innate immunityInnate immunity

Present at birth without any exposure Present at birth without any exposure Non-specificNon-specific

Acquired immunity/adaptive Acquired immunity/adaptive immunityimmunity Develops after exposureDevelops after exposure Highly specificHighly specific Recognition by lymphocytesRecognition by lymphocytes

Types of immunityTypes of immunity Natural immunityNatural immunity

Inherited immunity (parent to child)Inherited immunity (parent to child) Active immunityActive immunity

Long term immunity due toLong term immunity due to Exposure (i.e. chicken pox, mumps, Exposure (i.e. chicken pox, mumps,

measles)measles) VaccinationVaccination

Intentional exposure to weakened/dead pathogen Intentional exposure to weakened/dead pathogen or pathogenic toxinor pathogenic toxin

ImmunizationImmunization Polio...Polio...

Passive immunityPassive immunity Borrowed or temporary immunity Borrowed or temporary immunity

throughthrough Injection of antibodiesInjection of antibodies Blood serum or gamma globulin injectionsBlood serum or gamma globulin injections

Immediate immunityImmediate immunity Short term immunity Short term immunity

Memory cells are not producedMemory cells are not produced

Blood Groups effect on Blood Groups effect on transfusions & transplantstransfusions & transplants

Antibodies present against non-self Antibodies present against non-self blood types without exposureblood types without exposure result of reaction to bacterial antigensresult of reaction to bacterial antigens

MHC molecules stimulate immune MHC molecules stimulate immune response leading to tissue rejectionresponse leading to tissue rejection each person has a unique polymorphic each person has a unique polymorphic

combination of MHC moleculescombination of MHC molecules

Exaggerated, self-directed or Exaggerated, self-directed or diminished immune response & diminished immune response &

diseasedisease AllergiesAllergies

Hypersensitive response to antigens on Hypersensitive response to antigens on allergensallergens

Often involve IgE antibodiesOften involve IgE antibodies Attach to mast cells to induce histamine Attach to mast cells to induce histamine

releaserelease Anaphylactic shockAnaphylactic shock

Whole body, life threatening allergic reactionWhole body, life threatening allergic reaction Autoimmune diseaseAutoimmune disease

Body generates antibodies against selfBody generates antibodies against self Ex. Lupus, rheumatoid arthritis, multiple Ex. Lupus, rheumatoid arthritis, multiple

sclerosis, diabetes mellitussclerosis, diabetes mellitus

Immunodeficiency diseasesImmunodeficiency diseases Inborn or primaryInborn or primary

Caused by genetic or developmental defectCaused by genetic or developmental defect Defect in production of immune cells or Defect in production of immune cells or

specific proteinsspecific proteins Acquired or secondaryAcquired or secondary

Develops later in lifeDevelops later in life Caused by exposure to agents or diseaseCaused by exposure to agents or disease Ex. Hodgkin's, AIDSEx. Hodgkin's, AIDS