Immune SystemImmune System

Keeping you safeKeeping you safe

Good health is something you may take Good health is something you may take for granted.for granted.

Until you or someone close to you Until you or someone close to you gets sick.gets sick.

Then the value of good health Then the value of good health becomes all too obviousbecomes all too obvious

Why do you get sick?Why do you get sick? How do you get better?How do you get better? These are questions that can be These are questions that can be

answered!answered!

DiseaseDisease

Disease: any change other than an Disease: any change other than an injury that disrupts the normal injury that disrupts the normal functions of the bodyfunctions of the body• Some are inheritedSome are inherited• Some are caused by the environmentSome are caused by the environment• Some are caused by bacteria, viruses, Some are caused by bacteria, viruses,

and fungiand fungi

PathogensPathogens

Pathogens: disease causing agents- Pathogens: disease causing agents- such as- bacteria, virus, and fungisuch as- bacteria, virus, and fungi

Patho- sickness agentPatho- sickness agent Gen- to createGen- to create Infectious diseases- diseases caused Infectious diseases- diseases caused

by pathogens infecting the bodyby pathogens infecting the body

Germ Theory of DiseaseGerm Theory of Disease

I. I. • History of disease origin beliefHistory of disease origin belief

cursescurses evil spiritsevil spirits night vapors night vapors

Dispel History of Disease Origin Dispel History of Disease Origin BeliefsBeliefs

Louis PasteurLouis Pasteur Robert KochRobert Koch

Koch’s PostulatesKoch’s Postulates

Observations of both Koch and Observations of both Koch and Pasture was that:Pasture was that:

Disease is caused by microorganisms Disease is caused by microorganisms (germs)(germs)

Led to the Germ Theory of DiseaseLed to the Germ Theory of Disease World filled with microorganismsWorld filled with microorganisms Which microorganism actually Which microorganism actually

causes the disease?causes the disease?

Here’s the scenario:Here’s the scenario: 1975 Allen Steere at 1975 Allen Steere at

Yale University:Yale University:

Answered the question- which Answered the question- which microorganism causes a specific disease!microorganism causes a specific disease!

Small area of Connecticut- 39 children, Small area of Connecticut- 39 children, several adults suffered from joint pain and several adults suffered from joint pain and inflammation.inflammation.

Most cases in summer/ fallMost cases in summer/ fall Suspected could be pathogen carried by Suspected could be pathogen carried by

an insect.an insect. Many children reported infection began Many children reported infection began

with what they thought was an insect bite!with what they thought was an insect bite! Bite followed by expanding rashBite followed by expanding rash

Bull’s EyeRash

Lyme DiseaseLyme Disease

Steere called it Lyme DiseaseSteere called it Lyme Disease Linked skin rash to tiny deer tickLinked skin rash to tiny deer tick Dr. Willy Burgdorfer- Dr. Willy Burgdorfer-

• found spiral shaped bacterium in the found spiral shaped bacterium in the ticks (got to name the bacteria ticks (got to name the bacteria Borrelia burgedorferiBorrelia burgedorferi))

• found same spiral shaped bacterium found same spiral shaped bacterium in the patientsin the patients

Borrellia bergdorforiBorrellia bergdorfori

• injected bacteria into lab miceinjected bacteria into lab mice• mice got arthritis and other mice got arthritis and other

symptoms like the childrensymptoms like the children• Steere recovered the bacteria from Steere recovered the bacteria from

mice- passed on those bacteria to mice- passed on those bacteria to healthy micehealthy mice

• Healthy mice then got sickHealthy mice then got sick

Koch’s PostulatesKoch’s Postulates Burgdorfer and Steere relied on Koch’s Burgdorfer and Steere relied on Koch’s

(Pronounced Cock’s) Postulates(Pronounced Cock’s) Postulates Robert Koch Developed series of guidelines still Robert Koch Developed series of guidelines still

used today to identify pathogens that cause a used today to identify pathogens that cause a specific diseasespecific disease• 1) Pathogen should be found in sick organism and not 1) Pathogen should be found in sick organism and not

that of a healthy onethat of a healthy one• 2) Pathogen must be isolated and grown in lab in pure 2) Pathogen must be isolated and grown in lab in pure

cultureculture• 3) When purified pathogens placed in a new host, new 3) When purified pathogens placed in a new host, new

host get same disease that infected original hosthost get same disease that infected original host• 4) Injected pathogen should be reisolated from the 4) Injected pathogen should be reisolated from the

second host, should be identical to the original pathogensecond host, should be identical to the original pathogen

PathogensPathogens Agents of DiseaseAgents of Disease:: Why is the human body so good for Why is the human body so good for

pathogens?pathogens? right temperatureright temperature moist environmentmoist environment abundance of nutrientsabundance of nutrients Large Intestines: harbors dense colonies of Large Intestines: harbors dense colonies of

bacteriabacteria Mouth, throat, tissues surrounding eyeballs: Mouth, throat, tissues surrounding eyeballs:

bacteria and yeastbacteria and yeast Vaginal area: lots of yeast- Vaginal area: lots of yeast- -how do we get yeast infections?-how do we get yeast infections?

AntibioticsAntibiotics Antibiotics kill off the normal bacteria that Antibiotics kill off the normal bacteria that

keep yeast in check, with free reign of the keep yeast in check, with free reign of the area, yeast go to work and over produce area, yeast go to work and over produce causing a curd like substance to be causing a curd like substance to be produced, a.k.a.- yeast infection.produced, a.k.a.- yeast infection.

Question? How do pathogens cause Question? How do pathogens cause disease?disease?

bacteria can break down the tissuesbacteria can break down the tissues• parasites include protists, fungi and wormsparasites include protists, fungi and worms• some remove nutrients from digestive systemsome remove nutrients from digestive system• others destroy blood cells and neuronsothers destroy blood cells and neurons

bacteria can release toxins in the bacteria can release toxins in the bodybody

toxins: poisons that produce illness toxins: poisons that produce illness by disrupting bodily functionsby disrupting bodily functions

Botulism – Botulism – C. botulinumC. botulinum

Tetanus- Tetanus- C. tetani C. tetani found in soilfound in soil one of most powerful toxins/ does not allow one of most powerful toxins/ does not allow

muscles to go back to relaxed state. muscles to go back to relaxed state.

AnthraxAnthrax

Spread of DiseaseSpread of Disease

How Diseases are Spread:How Diseases are Spread: Some infectious disease can be spread Some infectious disease can be spread

from person to person through: from person to person through: • CoughingCoughing• SneezingSneezing• Physical ContactPhysical Contact• Contaminated waterContaminated water• FoodFood• Infected animalsInfected animals

VectorsVectors Vectors: animals, such as ticks and mosquitoes, Vectors: animals, such as ticks and mosquitoes,

spread many diseasesspread many diseases Vector: organisms that carry disease-causing Vector: organisms that carry disease-causing

agentsagents What was the vector for Lyme disease?What was the vector for Lyme disease? Often the key to stopping disease from spreadingOften the key to stopping disease from spreading Avoid tall grass will keep the deer tick awayAvoid tall grass will keep the deer tick away Wash Hands Wash Hands Good Hygiene Good Hygiene Avoid infected peopleAvoid infected people

STI’s (STD’s)STI’s (STD’s)

Sexually Transmitted Infections Sexually Transmitted Infections (STI’s)(STI’s)

diseases by exchange of bodily fluidsdiseases by exchange of bodily fluids also known as having sexalso known as having sex some of the most dangerous pathogens are some of the most dangerous pathogens are

spread by having SEXspread by having SEX

STI’s (STD’s)STI’s (STD’s)

Syphilis- caused by bacteria in body Syphilis- caused by bacteria in body fluidsfluids

Gonorrhea- caused by bacteria in Gonorrhea- caused by bacteria in body fluidsbody fluids

Chlamydia- caused by bacteriaChlamydia- caused by bacteria Hepatitis B&C- caused by virusHepatitis B&C- caused by virus AIDS- caused by virusAIDS- caused by virus

STI’s (STD’s)STI’s (STD’s)

Genital Herpes- caused by virusGenital Herpes- caused by virus Fighting Infectious Diseases:Fighting Infectious Diseases: If prevention fails (keeping pants on!) If prevention fails (keeping pants on!)

there are drugs that can possibly there are drugs that can possibly help to fight pathogens.help to fight pathogens.

Most useful drugs- antibioticsMost useful drugs- antibiotics

Antibiotics: compounds that kill Antibiotics: compounds that kill bacteria without harming the cells of bacteria without harming the cells of animals or humans by interfering animals or humans by interfering with the cellular processes of with the cellular processes of microorganismsmicroorganisms

Antiviral Drugs: inhibit ability of Antiviral Drugs: inhibit ability of viruses to invade cells and multiplyviruses to invade cells and multiply

DrugsDrugs

2 methods:2 methods: destroy cell wall of bacteria, so cannot live destroy cell wall of bacteria, so cannot live

(penicillin)(penicillin)• Fleming tried to grow Staphylococcus (a Fleming tried to grow Staphylococcus (a

bacterium), became contaminated with bacterium), became contaminated with Penicillium notatumPenicillium notatum. Fungus inhibited the growth . Fungus inhibited the growth of the bacterium.of the bacterium.

Blocks protein synthesis in the ribosome of Blocks protein synthesis in the ribosome of bacteria (streptomycin)bacteria (streptomycin)

• Antibiotics have NO effect on VirusAntibiotics have NO effect on Virus

Immune SystemImmune System

II. II. With all the pathogens scurrying With all the pathogens scurrying

about, why aren’t we always ill?about, why aren’t we always ill? We have a protective system known as We have a protective system known as

the Immune System: a series of the Immune System: a series of defenses that guard against disease.defenses that guard against disease.

some are simple barrierssome are simple barriers others are pistol packing security others are pistol packing security

guardsguards

Non-Specific DefensesNon-Specific Defenses

The Simple BarriersThe Simple Barriers 1st line of defense:1st line of defense:

• keep pathogens (the bad guys) outkeep pathogens (the bad guys) out• Skin is crucial, the most important Skin is crucial, the most important

barrier!barrier!

Non-Specific DefensesNon-Specific Defenses When blood shed begins (skin torn apart) When blood shed begins (skin torn apart)

pathogen allowed to enter and infectpathogen allowed to enter and infect Shows the pinnacle importance of skinShows the pinnacle importance of skin We’d be hopeless with out the skinWe’d be hopeless with out the skin Mouth and Nose:Mouth and Nose: Mucous- traps virus and bacteriaMucous- traps virus and bacteria Cilia- the gatekeeper pushes pathogens Cilia- the gatekeeper pushes pathogens

away from lungsaway from lungs Stomach acid and digestive enzymes:Stomach acid and digestive enzymes:

Non-Specific DefensesNon-Specific Defenses

Full on blitz, sneak past mucous and the Full on blitz, sneak past mucous and the gatekeeper (cilia) and reach stomachgatekeeper (cilia) and reach stomach

Destroy pathogensDestroy pathogens Lysozymes: enzymes that break down Lysozymes: enzymes that break down

bacteria cell wallsbacteria cell walls• Found in mucous, saliva, sweat and tearsFound in mucous, saliva, sweat and tears• 2nd line of defense:2nd line of defense:

(first line fail) Inflammatory response is (first line fail) Inflammatory response is next in linenext in line

Inflammatory responseInflammatory response Inflammatory response: a non-specific defense Inflammatory response: a non-specific defense

reaction to tissue damage caused by injury or reaction to tissue damage caused by injury or infection!infection!

Steps:Steps: Pathogen infects tissuesPathogen infects tissues Blood vessels dilate (expand)Blood vessels dilate (expand) White blood cells (leukocytes) leak from dilated White blood cells (leukocytes) leak from dilated

vessels and go to infected areasvessels and go to infected areas WBC are phagocytes: engulf and destroy bacteriaWBC are phagocytes: engulf and destroy bacteria Phago= to eatPhago= to eat Cyte= cellCyte= cell

Inflammatory responseInflammatory response

Hypothalamus: releases Hypothalamus: releases endogeneous pyrogenes (chemicals) endogeneous pyrogenes (chemicals) that increase core body temperaturethat increase core body temperature• This is a fever!This is a fever!

Higher temperature slows down or Higher temperature slows down or stops growth of pathogensstops growth of pathogens

Inflammatory responseInflammatory response

Higher temperature from fever Higher temperature from fever increases heart rate so that WBC get increases heart rate so that WBC get there fasterthere faster

Higher temperature speeds the activity Higher temperature speeds the activity of WBC’s and the reactions that help of WBC’s and the reactions that help repair damaged tissuesrepair damaged tissues

Interferons- help resist viral infectionsInterferons- help resist viral infections inhibit the synthesis of viral proteins inhibit the synthesis of viral proteins

therefore blocking viral replicationtherefore blocking viral replication

Specific DefensesSpecific Defenses::

Non-specific failure! Immune response Non-specific failure! Immune response becomes specific and varied- known as the becomes specific and varied- known as the IMMUNE RESPONSEIMMUNE RESPONSE

Triggered by Antigens: carbohydrates, Triggered by Antigens: carbohydrates, proteins, or lipids on a pathogen that proteins, or lipids on a pathogen that trigger the immune responsetrigger the immune response

Immune response can be humoral Immune response can be humoral immunity or cell- mediated immunityimmunity or cell- mediated immunity

Specific DefensesSpecific Defenses::

Humoral- immunity against pathogens in Humoral- immunity against pathogens in body fluids (blood and lymph)body fluids (blood and lymph)

Produced by lymphocytes Produced by lymphocytes • B- lymphocytes produce antibodiesB- lymphocytes produce antibodies

Antibody: protein that helps destroy a Antibody: protein that helps destroy a pathogenpathogen• Generally “Y” shapedGenerally “Y” shaped• Two identical antigen binding sites that bind to Two identical antigen binding sites that bind to

antigenantigen

Specific DefensesSpecific Defenses::

Influenza Virus: Here comes trouble Influenza Virus: Here comes trouble with a capital “I” (do antibiotics with a capital “I” (do antibiotics help?)help?)

Influenza enters- has antigen on Influenza enters- has antigen on surfacesurface

Antibody recognize virus as foreign Antibody recognize virus as foreign Begin to clump on (pile on top)Begin to clump on (pile on top)

Specific DefensesSpecific Defenses::

Phagocytes recognize clump (gobble Phagocytes recognize clump (gobble gobble) engulf and destroy mass!gobble) engulf and destroy mass!

How are antibodies produced? How are antibodies produced? Custom-made- specific to a specific Custom-made- specific to a specific

antigen!antigen! B-cells (B= bone marrow) made early in B-cells (B= bone marrow) made early in

fetus development:fetus development: Genes coding for antibodies rearrange Genes coding for antibodies rearrange

slightly differently in each B-cellslightly differently in each B-cell

Specific DefensesSpecific Defenses::

At end of development, due to slight At end of development, due to slight difference, there are millions of different difference, there are millions of different B-cells, each of which can recognize a B-cells, each of which can recognize a different antigendifferent antigen

So, when pathogen enters the body, a So, when pathogen enters the body, a small fraction of B-cells will recognize as small fraction of B-cells will recognize as foreign.foreign.

B-cells very happy and reproduce (split) B-cells very happy and reproduce (split) many copies made, known as plasma cells.many copies made, known as plasma cells.

Specific DefensesSpecific Defenses::

Plasma cells release the antibodies Plasma cells release the antibodies into blood stream to seek out and into blood stream to seek out and destroy the pathogen.destroy the pathogen.

Plasma cell activation and regulation Plasma cell activation and regulation monitored by T-lymphocytes (T= monitored by T-lymphocytes (T= thymus)thymus)

Specific DefensesSpecific Defenses::

Cell Mediated Immune Response:Cell Mediated Immune Response: Helper T regulate production of antibodies Helper T regulate production of antibodies

by B-cells, but other T cells can attack by B-cells, but other T cells can attack pathogens directly- called Killer T cells pathogens directly- called Killer T cells (cytotoxic T cells)(cytotoxic T cells)

Killer T’s transfer proteins into membrane Killer T’s transfer proteins into membrane that cause it to be “leaky” so fluid will leak that cause it to be “leaky” so fluid will leak out of the cell. Pathogen dies!out of the cell. Pathogen dies!

Killer T- why tough to do organ transplant: Killer T- why tough to do organ transplant:

Specific DefensesSpecific Defenses::

We will recognize our own organs by We will recognize our own organs by surface proteinssurface proteins

Everybody has different surface proteins Everybody has different surface proteins that will be recognized as foreign, immune that will be recognized as foreign, immune system will attack!system will attack!

Rejection is painful even at the organ Rejection is painful even at the organ level! (That’s why people resort to toilets)level! (That’s why people resort to toilets)

Must find very similar surface markers and Must find very similar surface markers and take drugs to suppress immune response take drugs to suppress immune response to prevent rejectionto prevent rejection

Permanent ImmunityPermanent Immunity

Been known for more than 2000 years Been known for more than 2000 years (measles/small pox- got once, never (measles/small pox- got once, never again)again)

Known as permanent immunity- done by Known as permanent immunity- done by memory B and T cells that are ready and memory B and T cells that are ready and armedarmed

Active ImmunityActive Immunity Edward Jenner: produced first vaccineEdward Jenner: produced first vaccine

Permanent ImmunityPermanent Immunity

Cowpox sufferers never got small Cowpox sufferers never got small pox?pox?

Could you infect someone with Could you infect someone with cowpox to prevent small pox?cowpox to prevent small pox?

Decided to infect Jamie Phipps with Decided to infect Jamie Phipps with fluid from cowpox sores.fluid from cowpox sores.

Jamie got cowpox.Jamie got cowpox.

Permanent ImmunityPermanent Immunity

Two months later, the mad scientist Two months later, the mad scientist Jenner took it one step further, Jenner took it one step further, infected Jamie with small pox. infected Jamie with small pox.

Surprise! Jamie did not die a horrible Surprise! Jamie did not die a horrible death from small pox!death from small pox!

The first vaccine discovered.The first vaccine discovered.

VaccinationVaccination

Vaccination: injection of a weakened or Vaccination: injection of a weakened or mild form of a pathogen to produce mild form of a pathogen to produce immunity (vacca means cow- from cowpox immunity (vacca means cow- from cowpox and cow hands and milk maids and and cow hands and milk maids and farmers and other people who deal with farmers and other people who deal with cows that gave Jenner the brilliant idea to cows that gave Jenner the brilliant idea to play with little Jamie)play with little Jamie)

Immunity from a vaccine is known as Immunity from a vaccine is known as ACTIVE immunity because body of ACTIVE immunity because body of recipient has the ability to respond recipient has the ability to respond immediately to exposure to the pathogen.immediately to exposure to the pathogen.

Passive Immunity:Passive Immunity:

If antibodies from another animal for a If antibodies from another animal for a particular pathogen are injected into our particular pathogen are injected into our bodies- the antibodies produce a passive bodies- the antibodies produce a passive immunity (only a few weeks) while they immunity (only a few weeks) while they are in the body.are in the body.

Often given to travelers (who will be in Often given to travelers (who will be in tropical areas for a limited time)tropical areas for a limited time)

Maternal immunity is a passive immunity Maternal immunity is a passive immunity (placenta/ milk provide antibodies)(placenta/ milk provide antibodies)

III. Immune System DisordersIII. Immune System Disorders

Although the immune system Although the immune system defends the body against all the evil defends the body against all the evil powers of the world, sometimes powers of the world, sometimes disorders occur.disorders occur.

Immune System DisordersImmune System Disorders

Two Main Types of Disorders:Two Main Types of Disorders: Immune system over reacts to Immune system over reacts to

antigens (the “girl response”) – antigens (the “girl response”) – produces discomfort or even diseaseproduces discomfort or even disease

Immune system is weak (the “boy Immune system is weak (the “boy response”) response”)

Immune System DisordersImmune System Disorders

Allergies (overreaction)Allergies (overreaction) Result when antigens from allergens Result when antigens from allergens

(things that create allergies, such as (things that create allergies, such as pollen, or another girl in the picture, or pollen, or another girl in the picture, or dust mites) bind to mast cells (another dust mites) bind to mast cells (another type of immune cell in the nasal passage)type of immune cell in the nasal passage)

Allergen antigen bind to mast cell, mast Allergen antigen bind to mast cell, mast cell release chemicals known as cell release chemicals known as histamines that increase blood and fluid histamines that increase blood and fluid flow to areaflow to area

Immune System DisordersImmune System Disorders

Histamines responsible for sneezing Histamines responsible for sneezing and runny nose and eyes and runny nose and eyes

Antihistamines for allergies?Antihistamines for allergies? Can result in asthma- smooth muscle Can result in asthma- smooth muscle

contractions reduce size of contractions reduce size of passageway of air in lungs- breathing passageway of air in lungs- breathing difficult- usually triggered by difficult- usually triggered by particular antigen (i.e. pollen)particular antigen (i.e. pollen)

Autoimmune DiseasesAutoimmune Diseases Immune attacks own body- yup, you guessed it, Immune attacks own body- yup, you guessed it,

an autoimmune disease!an autoimmune disease! Could be caused by an infectionCould be caused by an infection Example: strep throat (streptococcus bacteria) if Example: strep throat (streptococcus bacteria) if

left untreated will cause the immune system to left untreated will cause the immune system to produce antibodies to destroy the bacteria.produce antibodies to destroy the bacteria.

Antigens on streptococcus so similar to cardiac Antigens on streptococcus so similar to cardiac cells, immune response could also attack heartcells, immune response could also attack heart

Results in rheumatic fever: antibodies and killer T Results in rheumatic fever: antibodies and killer T cells kill and scar cells of the heart lining cells kill and scar cells of the heart lining (pericardium) and valves(pericardium) and valves

Autoimmune DiseasesAutoimmune Diseases

Example:Example:• Juvenile onset diabetesJuvenile onset diabetes• Multiple Sclerosis Multiple Sclerosis • AIDSAIDS

Example of cells of immune system Example of cells of immune system weakened by infectionweakened by infection

Autoimmune DiseasesAutoimmune Diseases Early 1980’s- Early 1980’s- People started coming down with infections People started coming down with infections

including:including: Protozoans in the lungsProtozoans in the lungs Fungal infections of the mouth and throatFungal infections of the mouth and throat Karposi Sarcoma (a rare skin cancer)Karposi Sarcoma (a rare skin cancer) Normal immune systems could battle these Normal immune systems could battle these

infections off like the weak advances Iraqisinfections off like the weak advances Iraqis Doctors soon realized that their patients’ immune Doctors soon realized that their patients’ immune

systems must be compromised. systems must be compromised.

HIV / AIDSHIV / AIDS

Way the disease was spread made Way the disease was spread made them suspect a virus.them suspect a virus.

1983- HIV identified (Human 1983- HIV identified (Human Immunodeficiency Virus) Immunodeficiency Virus)

HIV / AIDSHIV / AIDS The nuts and bolts:The nuts and bolts:

Virus enters body (HIV)Virus enters body (HIV) Attaches to receptors on T cellsAttaches to receptors on T cells T cells normally help recognize and aid immune T cells normally help recognize and aid immune

responseresponse Body does not produce antibodies to HIVBody does not produce antibodies to HIV HIV replicates within cells of immune system HIV replicates within cells of immune system

(because it is inside cells, less likely to bind to (because it is inside cells, less likely to bind to antibodies)antibodies)

NO CURE FOR AIDS NO CURE FOR AIDS Spread by contact with infected blood or other body Spread by contact with infected blood or other body

fluids (Oral/Anal still going to get it)fluids (Oral/Anal still going to get it) AbstainAbstain Faithful, get checked, latex condomFaithful, get checked, latex condom