Advanced BiologyAdvanced Biology

Chapter 22Chapter 22Nonspecific Body Nonspecific Body

Defenses and ImmunityDefenses and Immunity

Nonspecific – InnateNonspecific – Innate

Specific – AdaptiveSpecific – Adaptive

Intact skin and Intact skin and mucosamucosa

PhagocytesPhagocytesOther cells Other cells (inflammatory)(inflammatory)

Specific DefenseSpecific DefenseB Cells and T CellsB Cells and T Cells

Functional SystemFunctional SystemNo OrgansNo OrgansTrillions of CellsTrillions of Cells

Resistance to DiseaseResistance to Disease

NonspecificNonspecific

SpecificSpecific

Keratin provides a Keratin provides a barrier – resistant to barrier – resistant to weak acids/bases and weak acids/bases and bacterial toxinsbacterial toxins

Acidic – pH 3-5, Acidic – pH 3-5, inhibits bacterial inhibits bacterial growth; sebum growth; sebum contains chemicals contains chemicals toxic to bacteriatoxic to bacteria

Stomach – Stomach – concentrated HCl and concentrated HCl and protein digesting protein digesting enzymesenzymes

Saliva and lacrimal Saliva and lacrimal fluid contains fluid contains lysozyme which lysozyme which destroys bacteriadestroys bacteria

Sticky mucus traps Sticky mucus traps microorganismsmicroorganisms

MACROPHAGESMACROPHAGESDerived from Derived from monocytesmonocytes

Free MAC wander all Free MAC wander all overover

Kupffer cells -liverKupffer cells -liverAlveolar cells – LungsAlveolar cells – LungsPermanent residentsPermanent residents

WBC that can WBC that can phagocytizephagocytize

Neutrophils release Neutrophils release defensins – kills defensins – kills everything around it, everything around it, including itselfincluding itself

WBCWBCDefend against Defend against parasitic worms by parasitic worms by surrounding it and surrounding it and discharging enzymesdischarging enzymes

Some bacteria can Some bacteria can replicate inside MACs, replicate inside MACs, MACs are stimulated to MACs are stimulated to release other release other chemicals (Nitric oxide)chemicals (Nitric oxide)

Police the bodyPolice the bodyChecks markers – Checks markers – releases cytolytic releases cytolytic chemicalschemicals

Prevent Spread of Prevent Spread of damaging agentsdamaging agents

Dispose of cell debrisDispose of cell debris

Set stage for repairSet stage for repair

Enhance the body’s Enhance the body’s nonspecific defenses by nonspecific defenses by attacking microorganisms attacking microorganisms or hinder their ability to or hinder their ability to reproducereproduce

Classical – Binding of Classical – Binding of antibodiesantibodies

Alternative – Certain Alternative – Certain protein factors are protein factors are initiatedinitiated

Convergence on C3, Convergence on C3, Splitting it, C3a, C3b. Splitting it, C3a, C3b. Initiates events that Initiates events that cause lysis, promotes cause lysis, promotes phagocytosis and phagocytosis and enhances inflammationenhances inflammation

Message to tell other Message to tell other cells there is a viruscells there is a virus

Those cells synthesize Those cells synthesize “PKR” which interferes “PKR” which interferes with viral replicationwith viral replication

PyrogensPyrogensPyro – firePyro – fire

Causes liver/spleen Causes liver/spleen to retain zinc/ironto retain zinc/iron

Helps speed up Helps speed up metabolic rate of metabolic rate of cellscells

Can denature Can denature bacterial enzymesbacterial enzymes

Advanced BiologyAdvanced Biology

Chapter 22Chapter 22

Specific Body Specific Body Defenses: ImmunityDefenses: Immunity

Immune ResponseImmune Response

GoodGood

To mount an immune To mount an immune response is expensive. response is expensive.

Lots of energy is Lots of energy is required. Being specific, required. Being specific, energy is only expended energy is only expended

when necessary.when necessary.

Study of ImmunityStudy of Immunity

Antigen-SpecificAntigen-SpecificSystemicSystemicMemoryMemory

Humoral (Antibody-Humoral (Antibody-mediated)mediated)

Cellular (Cell-Cellular (Cell-mediated)mediated)

IntrudersIntrudersNot selfNot self

Immunogenicity – Immunogenicity – stimulate the stimulate the proliferation of specific proliferation of specific lymphocytes and lymphocytes and antibody productionantibody production

Reactivity – Ability to Reactivity – Ability to react with react with lymphocytes or lymphocytes or antibodiesantibodies

Part of antigen that is Part of antigen that is immunogenicimmunogenic

Binds to itBinds to it

Self-antigenSelf-antigenMajor Major Histocompatibility Histocompatibility Complex (MHC)Complex (MHC)

Class I MHC – All body Class I MHC – All body cellscells

Class II MHC – Immune Class II MHC – Immune Response CellsResponse Cells

Antigen Presenting Antigen Presenting Cells (APC)Cells (APC)

B Lymphocytes B Lymphocytes (Humoral)(Humoral)

T Lymphocytes (Cell T Lymphocytes (Cell mediated)mediated)

To be able to To be able to recognize a specific recognize a specific antigenantigen

Eliminates themEliminates them

Before meeting antigenBefore meeting antigen It is in your genesIt is in your genesAn antigen only An antigen only determines which B or T determines which B or T cell will proliferate and cell will proliferate and attackattack

Engulfs antigen, Engulfs antigen, shows it to a T cellshows it to a T cell

Advanced BiologyAdvanced Biology

Chapter 22Chapter 22

Humoral Immune Humoral Immune ResponseResponse

Not a game show Not a game show

11stst Encounter b/w Encounter b/w immunocompetent immunocompetent lymphocyte and lymphocyte and invading antigeninvading antigen

3 to 6 Days3 to 6 DaysTakes time for B cells Takes time for B cells to differentiateto differentiate

2ndry much faster, 2ndry much faster, more prolonged and more prolonged and more effective. 2-3 more effective. 2-3 day responseday response

See pg 775See pg 775

The capacity to The capacity to produce a powerful produce a powerful 2ndry humoral 2ndry humoral responseresponse

When B cells When B cells encounter antigens encounter antigens and produce and produce antibodies against antibodies against themthem

Naturally acquired: Naturally acquired: During bacterial & During bacterial & viral infectionsviral infections

Artificially acquired: Artificially acquired: Through vaccineThrough vaccine

Dead or attenuated Dead or attenuated (living but weakened) (living but weakened) pathogenspathogens

Spare us from most of Spare us from most of the symptomsthe symptoms

Provide functional Provide functional antigenic antigenic determinatesdeterminates

No memory is No memory is establishedestablished

Fetus to motherFetus to mother

ImmunoglobulinsImmunoglobulins

IgD – Attaches to B IgD – Attaches to B cells, activates B cellscells, activates B cells

IgM – Large, pentamer IgM – Large, pentamer shape. Antigen receptive, shape. Antigen receptive, 11stst Ig released during Ig released during primary response. Fixes primary response. Fixes and activates complementand activates complement

IgG – Most abundant – 75-IgG – Most abundant – 75-85%. Crosses placenta, 85%. Crosses placenta, protects against bacteria, protects against bacteria, viruses and toxins. Fixes viruses and toxins. Fixes complement.complement.

IgA – Dimer (2), found IgA – Dimer (2), found in body secretions, in body secretions, helps prevent helps prevent attachment of attachment of pathogens to epithelial pathogens to epithelial cellscells

IgE – Stem region is IgE – Stem region is bound to mast cells bound to mast cells and basophils and basophils (allergies)(allergies)

Antigen-Antibody Antigen-Antibody complexescomplexes

ComplementComplement

Neutralization – Neutralization – blocks specific sites blocks specific sites on viruses and on viruses and bacteriabacteria

Agglutination – Agglutination – Clumping of cellsClumping of cells

Precipitation – not rain.Precipitation – not rain.Antigen molecules, not Antigen molecules, not cells, are clumped cells, are clumped together.together.

See page 780.See page 780.

Advanced BiologyAdvanced Biology

Chapter 22Chapter 22

Cell-Mediated Cell-Mediated Immune ResponseImmune Response

Microorganisms that Microorganisms that slip inside body cellsslip inside body cells

Trying to avoid Trying to avoid immune systemimmune system

CD4 = T4, Helper TsCD4 = T4, Helper TsCD8 = T8, Cytotoxic CD8 = T8, Cytotoxic TsTs

Through processed Through processed parts on an APCparts on an APC

Provide means for Provide means for signaling to immune signaling to immune

system cells that system cells that infectious microorganisms infectious microorganisms

are hiding in body cellsare hiding in body cells

Step 1: Antigen BindingStep 1: Antigen BindingT cell antigen receptors, T cell antigen receptors, TCRs, bind to an TCRs, bind to an antigen-MHC protein antigen-MHC protein complexcomplex

Helper Ts bind to MHC Helper Ts bind to MHC II – w/help of APCII – w/help of APC

Cytotoxic Ts bind to Cytotoxic Ts bind to MHC I – needs no APCMHC I – needs no APC

Step 2: CostimulationStep 2: Costimulation If bound to right costimulator If bound to right costimulator

(protein, chemicals), (protein, chemicals), stimulation (proliferation) stimulation (proliferation)

occurs. W/O right match, T occurs. W/O right match, T cell activity is stoppedcell activity is stopped

Mediators involved in Mediators involved in cellular immunitycellular immunity

Lymphokines – Lymphokines – released by activated released by activated T cellsT cells

Monokines – secreted Monokines – secreted by MACsby MACs

Interleukin 1 & 2 – IL 1 Interleukin 1 & 2 – IL 1 released by MACs tells released by MACs tells T cells to liberate IL 2, T cells to liberate IL 2, which encourages T which encourages T cells to divide more cells to divide more rapidly.rapidly.

Tumor Necrosis Tumor Necrosis Factor (TNF) – Factor (TNF) – enhances nonspecific enhances nonspecific cell killingcell killing

Perforin/lymphotoxin Perforin/lymphotoxin are cell toxins that T are cell toxins that T cells can release. cells can release. Lethal Hit.Lethal Hit.

Gamma Interferon – Gamma Interferon – enhance killing power enhance killing power of MACsof MACs

Regulatory cellsRegulatory cellsInteract with B cellsInteract with B cells

Major function is to Major function is to chemically or directly chemically or directly stimulate proliferation of stimulate proliferation of other T cells and B cells other T cells and B cells that have already that have already become bound to antigenbecome bound to antigen

W/O helper Ts, there W/O helper Ts, there is no immune is no immune response!!response!!

Killer T cellsKiller T cellsThey can directly They can directly attack and kill other attack and kill other cellscells

Main target is virus infected Main target is virus infected cells, also tissue cells that cells, also tissue cells that

have been infected, have been infected, parasites, cancer cells, parasites, cancer cells,

foreign cells introduced by foreign cells introduced by blood transfusions or organ blood transfusions or organ

transplantstransplants

Help stop immune Help stop immune response after response after antigen has been antigen has been destroyeddestroyed

Promote allergic Promote allergic reactionsreactions