Types of Immunity for Class

7/30/2019 Types of Immunity for Class

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Immunology


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Immunology the science that encompassesthe body's defense mechanically.

Immune system a defense system developedin vertebrates.

Protection against pathogenic microbes andcancer.


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The Nature of Disease

Pathogenic Organisms Genetic Disorders Toxic Chemicals Other Environmental Factors Physical Damage to Organs

Nutritional Disorders


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Types of Pathogenic Organisms

Viruses Bacteria Protozoan Fungi

Animal Parasites


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Mechanisms of Diseaseby Pathogens

Utilization of host nutritionalresources

Physical damage to host tissues Production of toxic substances Chromosomal and gene damage Body cells behave abnormally


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Immune response has 2 interrelated activities: Recognition- between 2 foreign pathogens

-Discriminate between self and foreign

Response- Effector response

- Memory response


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Immunity State of protection from infectiousdiseases.

Immune response reaction of the bodyagainst foreign antigen.


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Types of immunity

Innate immunity (Native immunity)Resistance by virtue of genetic and constitutional make

up Specific Non-specific species Racial Individual


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Species immunity-eg: humans unsusceptible to plantpathogens and many animal pathogens

Racial immunity-eg: resistance of algerian sheep to

anthrax.People of negroid origin susceptible to TB than

caucasians

Individual immunity- eg:factors like age, hormonalinfluence, nutrition e tc


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Defensive barriers

Anatomic barriers Physiologic barrier

Endocytic and phagocytic barrier Inflamatory barrier


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Skin acts as barrier to microbes and viruses- sweat has a low pH- sebaceous glands

Mucus traps foreign particles

Tears Saliva

Anatomic barriers


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Body Coverings: The Skin

sebaceousglands

sweat gland

epidermis


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Body Coverings:Mucous Membranes

mucus

cilia

columnarepithelium


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Temperature pH Oxygen tension Gastric acidity Soluble proteins like:

- Lysozyme- hydrolytic enzyme in mucous secretions,can cleave PG layer

- Interferon- proteins produced by virus infected

cells, can bind to nearby cells and inducegeneralised antiviral state- Complements- group of serum proteins that

circulate in a inactive proenzyme state which can be

activated to destroy pathogens

Physiologic barriers


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Endocytic and Phagocytic barriers

Endocytosis- Process of internalization of macromolecules. By formation of endocyticvesicles by the PM.

Endocytosis occurs through Pinocytosis orreceptor mediated endocytosis.

Pinocytosis- internalization through non-specific

membrane invaginations Receptor mediated endocytosis- selective

internalization by binding to membrane receptors


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After internalization- endoytic vesicles fuseand are delivered to endosomes

In endosomes macromolecules are lysed bylysosymes from golgi complex in to smallerproducts like peptides, sugars, nucleotides etc

This is called the endosomal processingpathway.


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Phagocytosis- ingestion of particulate matterincluding whole pathogenic microorganism.

PM expands around the particulate materialto form a large vesicle called phagosome 10-20 times larger than the endocytic vesicle.

Only specialised cells can phagocytose eg

Monocytes, Neutrophils, Macrophages Phagosome fuse with lysozome and ingested

material is digested


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Nonspecific Phagocytosis

Neutrophils

MonocytesEosinophils


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Mechanism of Phagocytosis

Macrophage


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Lymphatic System


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Inflamatory barrier

Tissue damage caused by a wound or invasionof a pathogenic microorganism induces aInflammatory Response.

3 main events occur: Vasodilation Increased capillary permeability Influx of phagocytic cells


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Vasodilation:

Increase in the diameter of blood vessels due toconstriction of blood vessels that carry bloodaway from the affected area- results inengorgement of the capillary network

Cause Erythema- tissue redness


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Increase in capillary permeability:

Influx of fluids from engorged capillaries intotissues.

This fluid is called Exudate causes Edema tissue swelling


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Influx of phagocytic cells:Capillary permeability facilitate migration of WBCs

from capillary to tissues.

Emigration of phagocytes involve a complex seriesof events including cellular adherence -(Margination ) to endothelial wall

-emigration between capillary endothelial cells intotissues DIAPEDESIS or EXTRAVASATION

- Migration through tissue to site of response-Chemotaxis.


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Phagocytic cells accumulate and phagocytosebacteria , release lytic enzymes that candamage nearby healthy cells .

Accumulation of dead cells, digested materialand fluid form a substance called PUS


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Inflammatory Response

Histamine &prostaglandinsreleased

Capillaries dilateClotting begins

Chemotacticfactors attractphagocytic cells

Phagocytesconsumepathogens & cell

debris


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Acquired Immunity

Active Immunity

- Naturally-Acquired Active Immunity

- Artificially-Acquired Active Immunity

Passive Immunity

- Naturally-Acquired Passive Immunity- Artificially-Acquired Passive Immunity


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Active Immunity

Resistance developed as a result of antigenicstimulus

Active functioning of Immune system Synthesis of antibodies Production of immunologically active cells

Long lasting associated with immunologicalmemory.


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Artificial active immunity: resistance induced by vaccines Vaccines are preparations of live or killed microorganisms

or their products used for immunisation Eg: Bacterial vaccines:

Live- BCGkilled- TAB

Viral vaccines:Live- OPV

Killed- salk for polioBacterial products- toxoids for diphtheria and tetanus


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Live vaccines- initiate infection withoutcausing injury or disease.

Immunity similar to natural infection. Lasts for several years, boosters

recommended Administration can be oral or parenteral


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Killed vaccines less immunogenic Protection for short period Administration repeatedly, atleast 2 doses for

immunity, primary dose and booster dose.


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Passive immunity

Resistance transmitted to a recipient in aready made form.

Recepients immune system plays no activerole

No antigenic stimulus, preformed antibodiesare administered

Protection immediate Immunity for days or weeks


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Natural passive immunity:

Resistance transferred from mother to baby,through placenta in humans, and in animalsthrough colostrum.

Human colostrum is rich in IgA.

Human foetus acquires ability to syntiesizeantibodies from 20 th week of life.

Maternal antibodies give passive protection


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Artificial passive immunity:Transferred by administration of antibodies.

Agents used- hyperimmune sera of animal or humanorigin.

Eg antitetanus serum ATS

Tetanus toxoids are injected to horse, blood iscollected and serum separated , antibodies areconcentrated and purified.

Administration- subcutaneous for prophylaxis, IV fortreatment.

Passive immunisation- provides immedaite andtemporary protection in a non immune host.


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Types of AcquiredImmunity


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The production of antibodies against aspecific disease by the immune system.

Naturally acquired through disease Artificially acquired through vaccination

Vaccines include inactivated toxins, killedmicrobes, parts of microbes, and viable but

weakened microbes. Active immunity is usually permanent

Active Immunity


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A vaccinated person has a secondaryresponse based on memory cells when

encountering the specific pathogen. Routine immunization against infectious

diseases such as measles and whoopingcough, and has led to the eradication of smallpox, a viral disease.

Unfortunately, not all infectious agents areeasily managed by vaccination.

HIV vaccine in the works


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Passive Immunity - Protectionagainst disease through antibodies

produced by another human beingor animal. Effective, but temporary Ex. Maternal antibodiesColostrum.

Passive Immunity


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Passive immunity can be transferredartificially by injecting antibodies from an

animal that is already immune to a diseaseinto another animal. Rabies treatment: injection with antibodies

against rabies virus that are both passiveimmunizations (the immediate fight) and activeimmunizations (longer term defense).

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Types of Immunity for Class