Principles of Immunology: An Introduction to the Immune System

7/30/2019 Principles of Immunology: An Introduction to the Immune System

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LABSCI 200

Midterm Lecture 1

Principles of Immunology:

An Introduction to theImmune System


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The Immune System

Functions of the Immune System:

For homeostasisDefense against infectious agents

For surveillance


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Terminologies

Immunity bodys defense against an antigen

Antigen (Ag) substances that cause the body

to produce specific Abs

Antibody (Ab) Proteins made in response to an Ag

Serology Study of reactions bet. Abs & Ags

Globulins Serum proteins

Gamma globulin Serum fraction containing Ab


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White Blood Cells

Neutrophils: _________________

Basophils: _________________

Eosinophils: _________________

Monocytes: _________________

Lymphocytes: _________________


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Host Defenses

Figure 16.1


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Nonspecific Host Defenses

Susceptibility Lack of resistance to adisease

Resistance Ability to ward off disease Nonspecific resistance Defenses against any

pathogen

Specific resistance Immunity, resistance to aspecific pathogen


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Mechanical Factors

MUCOUS MEMBRANES

Ciliary escalator

Lacrimal apparatus Saliva

Urine

Vaginal secretions

SKIN

Epidermis consists of tightly packed cells with

Keratin, a protective protein

FIRST LINE OF DEFENSE


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Chemical Factors

Fungistatic fatty acid in sebum

Low pH (3-5) of skin

Lysozyme in perspiration, tears, saliva & tissuefluids

Low pH (1.2-3.0) of gastric juice

Transferrins in blood find iron

NO inhibits ATP production


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SECOND LINE OF DEFENSE


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Microbial Evasion of Phagocytosis

Inhibit

adherence

M protein

capsules

Kill phagocytes Leukocidins

Lyse

phagocytes

Membrane

attack complex Escape

phagosome-

Prevent

phagosome-lysosomefusion

-

Survive inphagolysosome

-


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Functions: contain & isolate the injury

destroy microorganisms/ toxins

prepare tissue for healing & repair

Cardinal Signs :

Rubor

Tumor

Calor

Dolor

Functio Laesa.


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Chemicals Released by Damaged Cells

Histamine Vasodilation Kinins Vasodilation

Prostaglandins Intensify histamine and kinin

effect

Leukotrienes Increased permeability of

blood vessels, phagocytic

attachment


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Classical Pathway

Figure 16.13

AlternativePathway


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Serum proteinsactivated in acascade.

Figure 16.10

Common Pathway


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Cytokines

Interleukin 1 mediator of leukocytic population

IL-1

IL-2

IL-12

Chemokines

induce WBC migration


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Interferon from a virus-infested cell

-Interferon(Increase activity of macrophages)

Tumor Necrosis Factor

inflammatory reactions

GMColony Stimulating Factor

stimulate production of WBCs


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Specific Host Defenses :The Immune Response

Acquired immunity Developed during an

individual's lifetime

Humoral immunity Involves Ab produced

by B cells

Cell-mediated immunity Involves T cells


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Acquired Immunity

Naturally acquired active immunity

Naturally acquired passive immunity

Artificially acquired active immunity

Artificially acquired passive immunity


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Antigenic Determinants

Figure 17.3

Haptens


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IgG IgE

80% of serum Abs

Cross placenta

Enhance phagocytosis; neutralize toxins & viruses;

protects fetus & newborn

0.002% of serum Abs

On mast cells andbasophils, in blood

Allergic rxns; lysis ofparasitic worms

IMMUNOGLOBULINS


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IgM 5-10% of serum antibodies

1st Ab produced in response to

infection

In blood, lymph, on B cells

Agglutinates microbes


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IgA IgD

10-15% of serum Abs

In secretions Mucosal protection

0.2% of serum Abs

On B cells, initiateimmune response


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Figure 17.10


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HUMORAL IMMUNITY

Involves Ab production

Defends primarily against:

Bacteria Bacterial toxins

Viruses (in body fluids)

Transplanted tissues


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B CELLS

Figure 17.8

h l f b d


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The Results of Ag-Ab Binding

Figure 17.9


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CELL-MEDIATED IMMUNITY

Involves T-cells

Most effective against:

Intracellular Bacteria & viruses

Fungi

Protozoa

Helminths

ll


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T Cell CD4, TH

TH1 TH2

CD8, TC Destroy target cells with perforin

TD

allergies, transplant rejection, and TB skin test

TS

Turn off immune response


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Antibody Production

Figure 17.16

C ll di d C i i


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Cell-mediated Cytotoxicity

Figure 17.14


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A. Hypersensitivity Reactions

Response to antigens (allergens)

leading to damage

Require sensitizing dose(s)

DISEASES of the IMMUNE SYSTEM

T I (A h l ti ) R ti


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Type I (Anaphylactic) Reactions

Involves IgE

Localized: Hives or

asthma

Systemic: Shock

Figure 19.1a


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Type II (Cytotoxic) Reactions

Involves IgG or IgM and complement

Complement activation causes cell lysis ordamage by macrophages


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Type III (Immune Complex) Reactions

Figure 19.6


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Type IV (Cell-Mediated) Reactions

Delayed-typehypersensitivitiesdue to TD cells

Cytokines attractmacrophages and

initiate tissuedamage

Figure 19.8

B AUTOIMMUNE DISEASES


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B. AUTOIMMUNE DISEASES

Type I Due to Ags against pathogens

Type II Abs react with cell-surface Ags

Type III IgM, IgG, complement immunecomplexes deposit in tissues

Type IV Mediated by T cells

C IMMUNE DEFICIENCIES


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C. IMMUNE DEFICIENCIES

Congenital:

Selective IgA immunodeficiency

Severe combined immunodeficiency

Acquired:

Artificial: Immunosuppressive drugs

Natural: HIV infections

Th I S t d C


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The Immune System and Cancer Cancer cells possess tumor-specific antigens

TC cells recognize and lyse cancer cells

Cancer cells may lack tumor antigens or kill TC cells

Figure 19.11

IMMUNOTHERAPY

Treatment of cancer using immunologic methods

TNFs, IL-2, and interferons may kill cancer cells

Vaccines contain tumor-specific antigens


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Medical Parasitology

deals with human parasites and

their medical significance as well astheir importance in human

communities


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HELMINTHS

Eukaryotic

Multicellular animals

ChemoheterotrophicKingdom:Animalia

Phylum:Nematodes

Phylum:Platyhelminthes


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GENERAL TYPES OF PARASITES

1. Ectoparasites2. Endoparasites

TYPES OF HOSTS

1.Intermediate Hosts

2. Definitive Hosts

SOURCES OF INFECTION


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SOURCES OF INFECTION

1. Contaminated soil & water2. Contaminated food

3. Consumption of undercooked

or raw fish4. Arthropods

5. Beddings of infected person

6. Infected food handlers


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MODES OF TRANSMISSION

1. Fecal-Oral route

2. Skin penetration

3. Bites of arthropods

4. Congenital infection

5. Inhalation of airborne eggs

6. Sexual intercourse


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ARTHROPODS

Kingdom:Animalia

Phylum:Arthropoda

Types of Involvement Cause of disease

Intermediate host

Definitive host

Vector


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Class Insecta (insects)

Reduviid bugs

Lice

Mosquitoes

Fleas

Flies

Class Arachnida (arachnids)

Mites

Ticks

Class Crustacea (crustaceans)

Crabs

Crayfish

Cyclops


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NEMATODESINTESTINAL NEMATODES

Ascaris lumbricoidesEnterobius vermicularis

Necator americanus

Strongyloides stercoralis

Trichuris trichiura


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1. Ascaris lumbricoides

COMMON NAME:Large Intestinal Roundworm

INTERMEDIATE HOST: -

DEFINITIVE HOST: HumanACQUIRED BY: Ingestion of Eggs

DX: Observation of eggs in stool

INFECTIVE STAGE: Embryonated eggDIAGNOSTIC STAGE: ova


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2. Enterobius vermicularis

COMMON NAME: PinwormINTERMEDIATE HOST: -

DEFINITIVE HOST: Human

ACQUIRED BY: Ingestion of Eggs

DX: eggs in Scotch Tape Method

INFECTIVE STAGE: Embryonated eggsDIAGNOSTIC STAGE: Eggs on perianal folds


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3. HOOKWORMS

INTERMEDIATE HOST: -


ACQUIRED: Skin penetration by larva

DX: eggs in stool specimens

INFECTIVE STAGE: Filariform larvaDIAGNOSTIC STAGE: Ova


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4. Strongyloides stercoralis

COMMON NAME: ThreadwormINTERMEDIATE HOST: -


ACQUIRED: Skin penetration by larva

DX: eggs/larva in duodenal aspirates orstool

INFECTIVE STAGE: Filariform larva

DIAGNOSTIC STAGE: Rhabditiform larva


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5. Trichuris trichiura

COMMON NAME: WhipwormINTERMEDIATE HOST: -


ACQUIRED: Ingestion of eggs

DX: eggs in stool specimens

INFECTIVE STAGE: Embryonated eggDIAGNOSTIC STAGE: Eggs


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TISSUE NEMATODES

1. Dracunculus medinensis2. Trichinella spiralis


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1. Dracunculus medinensis

CN : Guinea WormI.H.: Cyclops(fresh water crustacean)

D. H.: Human

ACQUIRED: Ingestion of infected Cyclops

DX: adult worm beneath the skin oremerging from a blister(ankle or foot)

I.S.: Larva in fresh water fish

D. S.: Adult worm


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2. Trichinella spiralis

IH/DH: Pig, Bear, Walrus,Human

ACQUIRED: Ingestion of meat with larva

DX: Mostly undiagnosed or incidental finding

I.S./ D.S.: Encysted larva in striated muscles


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FILARIAL NEMATODES

1. Brugia malayiWuchereria bancrofti

2. Loa loa

3. Onchocerca volvulus

B i l i


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Brugia malayiWuchereria bancrofti

I.H.:mosquitoes

D.H.:Human

ACQUIRED:Injection of larvae by mosquitoDX:microfilariae in stained blood smears

I.S.:L3 (3rdstage larvae)

D.S.:microfilariae

L l


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Loa loa

CN: Eye WormI.H.:Chrysops( Mango Fly).

D.H.: Human

ACQUIRED: Injection of larvae by Chrysops

Dx: adult worm beneath skin or in the

conjunctivaI.S.:L3 (3rd stage larvae)D.S.:microfilariae


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Onchocerca volvulus

CN:Blinding WormIH:Simulium(Black Fly).

DH:Human

ACQUIRED:Injection of larvae by Simulium

DIAGNOSED: microfilariae in skin snips

I.S.:L3 (3rd stage larvae)

D.S.:microfilariae

CESTODES


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CESTODESINTESTINAL CESTODES

Diphyllobothrium latum

Dipylidium caninumHymenolepis diminuta

Hymenolepis nana

Taenia saginata

Taenia solium


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Diphyllobothrium latum

CN: Fish Tapeworm

IH: Cyclops (1st IH)

Fresh Water Fish (2nd IH)

DH: HumanACQUIRED: Ingestion of fresh H2O fish withL2

DX: proglottids or eggs in stoolIS: procercoid larva

DS: unembryonated eggs

Di lidi i


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Dipylidium caninum

CN: Dog Tapeworm

IH: Flea

DH: Dog, Cat, Human

ACQUIRED:Ingestion of infectedflea

DX:proglottids / egg packets in

stoolI.S.: cysticercoid

D.S.:proglottid

H l i di i t


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Hymenolepis diminuta

CN: Rat Tapeworm

IH: Beetle

DH: Rat, Mouse, Human

ACQUIRED:Ingestion of beetleDX: egg in stool

INFECTIVE STAGE:embryonated egg

DS:embryonated egg (absence of proglottid)

H l i


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Hymenolepis nana

CN: Dwarf Tapeworm

IH: -

DH: Human

ACQUIRED: Fecal-Oral routeDX: egg or proglottids in stool

INFECTIVE STAGE: embryonated egg

DS: embryonated egg (no proglottid)


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TISSUE CESTODE


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TISSUE CESTODE

Echinococcus granulosus

IH: Sheep, Human (dead-end)

DH: Dog

ACQUIRED: Ingestion of eggs

DX: cysts by CT scans, MRI, x-ray, serotests

DS: eggs or proglottids in stool

TREMATODES


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1. Adults have oral and ventral suckers.2. Hermaphroditic.

3. Requires 2 IH in their life cycle.

4. Eggs are operculated.5. Infective stage ismetacercaria (in 2nd IH).

6. 1st IH is always asnail.

7. 2nd IH:fish, crustacean, snail, fresh H2Oplants.

8. Grouped together based on their habitat.

TREMATODES

INTESTINAL TREMATODE


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Fasciolopsis buski

CN: Intestinal Fluke

IH: Fresh Water Snails

DH: Human, Dog, Pig, RabbitACQUIRED: Ingestion of raw or uncooked

plants with metacercariae

DIAGNOSED: eggs in stool specimens

LIVER TREMATODE


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Clonorchis sinensis

CN: Chinese or Oriental

Liver Fluke

IH: Fresh Water Snails (1st)

Fresh Water Fish (2nd)

DH: Human, Dog, Cat

ACQUIRED: Ingestion of fresh water fishDX: eggs in stool

LIVER TREMATODE


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LIVER TREMATODE

Fasciola hepatica

CN: Liver Fluke

IH: Fresh Water SnailsDH: Human, Cow, Sheep

ACQUIRED:Ingestionof raw or undercooked

aquatic vegetation with metacercariaeDIAGNOSED: eggs in stool specimens


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Paragonimus westermani

CN: Lung Fluke

IH: Fresh Water Snails(1ST)

Crabs or Crayfish (2ND)DH: Human, Dog, Cat

ACQUIRED:

Ingestion of crabs or crayfishDX: eggs in sputum or stool

BLOOD TREMATODES


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Schistosoma

CN: Blood Fluke

IH: Fresh Water Snails

DH: HumanACQUIRED: Skinpenetration by

cercariae

DX: eggs in urine (S. haematobium)or stool (S. japonicum & S.mansoni)


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PROTOZOA

eukaryotic

single-celled

animal-likemostly free-living

soil & waterbreak down & absorbnutrients from host


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SUBPHYLUM Sarcodina:


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Amebiasis;

Amebic Dysentery;

Extraintestinalamebic abscesses

ACQD: ingestion of cysts

DX: cysts &/ trophozoitesin stool

Entamoeba histolytica


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Naegleria fowleri

Primary AmebicMeningoencephalitis

ACQD: diving in ponds

DX: trophozoites in CSF

cysts in tissue

i h


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SUBPHYLUM Mastigophora

Giardia lamblia

Trichomonas vaginalis

Leishmania spp Trypanosoma brucei

Trypanosoma cruzi

Giardia lamblia


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Giardia lamblia

GiardiasisACQD: ingestion of cysts

DX: trophozoites or cysts in stool



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Trichomoniasis Vaginitis

ACQD: contact; STD

DX: trophozoites ingenital discharges,prostatic secretions

Leishmania


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Leishmania

Leishmaniasis

ACQD: bite of sand fly (Phlebotomus)

DX: parasite in aspirates or biopsyspxns

Trypanosoma brucie


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Trypanosoma brucie

African Trypanosomiasis

(African Sleeping Sickness)

ACQD: bite of Tsetse fly

DX: trypomastigotes in bld,CSF, LNaspirates

Trypanosoma cruzi


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Trypanosoma cruzi

American Trypanosomiasis(Chagas Disease)

ACQD: orgs in Reduvid bug feces getsrubbed into bug bite

DX: trypomastigotes in spxn

SUBPHYLUM Ciliata


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Balantidium coli

Balantidiasis

(a dysenteric disease)

ACQD: Ingestion of cysts

DX: cysts / trophozoites in stool

SUBPHYLUM S


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SUBPHYLUM Sporozoa

Cryptosporidium parvum

Plasmodium spp

Toxoplasma gondii



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Cryptosporidiosis

(a diarrheal disease)

ACQD: Ingestion of oocystsDX: oocysts in feces

Toxoplasmosis

ACQD: Ingestion of oocysts in catfeces / cysts in meat

DX: Immunodiagnosis

Toxoplasma gondii

Plasmodium species


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ACQD: Injection of sporozoites byfemale Anopheles mosquito

DX: trophozoites, schizonts,gametocytei bl d

Malaria

P. falciparumP. malariaeP. ovale

P. vivax

Principles of Immunology: An Introduction to the Immune System

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Principles of Immunology: An Introduction to the Immune System