What is Immunity? Explain the types of Immunity? (Presentation)

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IMMUNOLOGY

Satish Kumar.I www.Biochemden.in

www.BiochemDen.inwww.CsirNetLifeSciences.com

http://www.biochemden.in/

http://www.csirnetlifesciences.com/

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Immunology means,

“Immunology is the science that studies the structure and functioning of the Immune system”.

Basically , IMMUNOLOGY is the study of the Immune response.


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2. Long term immune responses, which represents our actual immune system.

Strategies of Resistance:

1. Immediate destruction of parasites on surface layers by secretions of some

chemicals. (E.g.: Enzymes, Lysozymes, acids, etc.)

3. Immediate immune response, collectively referred as phagocytosis, Inflammatory

reactions.


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The term IMMUNITY,

Originally denoted freedom from some kind of service to the Roman state; now in

medical terms, it denotes

“freedom from disease”

It is Latin word, “immunis” that means

“free of burdens”


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Immunity shows TWO related activities

Response

Recognition&


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Types of Immunity

IMMUNITY

Innate Immunity Acquired Immunity


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1.Innate Immunity:

These are also referred as

“Non-specific immunity”

This type of immunity shown any “non-self” material. These are the first line defense against infection. This Innate immunity can be divided into TWO types,

External Innate immunity (First line defense)

Internal Innate immunity (Second line defense)


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External Innate Immunity

Physical barriers

Skin, is the largest water proof (9.7m2) and germ proof self-disinfecting, defense organ

Mucous membranes, Mucus secreted by mucus gland traps the pathogens and immobilizes them.

Mucus is clear, sticky mixture of mucin (glycoprotein) and water.

It is present in all intestinal tract.

The external defense comprises physical and chemical barriers to the entry of pathogens into the body.


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Chemical barriers1. Oily and sweat secreted by integument make the skin

acidic.

2. Saliva of buccal cavity contains LYSOZYME which kill the microorganism.

3. GUT secretions like HCl provides acidic medium which inhibits the growth of microbes.

4. Bile offers alkaline medium which check the growth of microorganism in intestine.

5. The lacrymal glands secrete tears containing lysozyme which prevent eye infections.

6. Cereminous glands of auditory canal secrete cerumen (ear wax) which traps the dust and bacteria.

7. Vaginal bacteria produce lactic acid from the glycogen thereby producing acidic environment to vagina as female’s best natural defense against pathogens.


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Body’s internal defense involve the participation of cellular and non-cellular factors possessing antibacterial property which have been found in blood and tissues.

Internal Innate Immunity

It is a

“Second line defense”These factors can be discussed under following heads.

1. Biochemical factors

2. Cellular factors

3. Other factors


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1.Biochemical factors:

The major biochemical factors are

Interferon

Complement system

Cellular factors


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a) Interferon:

A special defense system works specially against viral infection they offers resistance by blocking viral mRNA transcription thereby disrupting the viral life cycle.

These are group of soluble, non toxic glycoproteins produced in small amount by all the cells of the body.


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b) Complement systemComplement system comprises set of 11 proteins found in the serum.

A series of 11 proteins that are activated by antigen-antibody complexes.

Activation of the complement increases the phagocytosis and destruction of the microbial organisms that enter the body of an individual.

The system perform function in different ways-

1. Complement proteins ruptures the cell membranes of microbes.

2. Stimulates mast cells to produce histamine

3. Strengthens the inflammatory reaction

4. Act as chemokines

5. Attract the phagocytes to the infected area.Satish Kumar.I www.Biochemden.in

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c) Cellular factors

The phagocytic cells were originally discovered by

“Metchnikoff (1883)”

The phagocytic cells are of two types-

i) Microphages

ii) Macrophages

iii) Natural killer cells


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i) Microphages

Microphages are

“Polymorphonuclear leucocytes”

These are of Three types,

Neutrophils

Basophils

NeutrophilsSatish Kumar.I

www.Biochemden.in

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ii) Macrophages

Macrophages are the cells of the Mononuclear phagocytic system was originally called as

“Reticuloendothelial system (RES)”

A major function of RES is

“The removal of RES is the removal of foreign material that enter the body”.


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iii) Natural Killer cells:

These are the type of Lymphocytes

The cells lyses the (burst open) the viral

infected body cells and abnormal cells which

could form tumors


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Other factors

“Fever”

&

“Inflammatory reactions”


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A sudden rise in body temperature (pyrexia) following an infection is an natural defense mechanism.

In Fever ,

Stimulates the production of Interferon,

Increases WBC count of blood .

Fever

Rise in temperature accelerate the physiological process and destroys the infecting pathogens.

Mild fever strengthens the defense mechanism by activating phagocytes and by inhibiting growth of bacteria Satish Kumar.I

www.Biochemden.in

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Inflammatory reactions

This is a non-specific defense response by the body to an injury in the tissue.

The injured area shows the following characteristic signs of inflammation.

i) A red color from blood accumulation – RUBOR

ii) A warmth from the heat of blood –CALOR

iii) A swelling from the accumulation of fluid – TUMOR

iv) Pain from injury to the local nerves - DOLOR


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2) Acquired Immunity

“This immunity develops due to an exposure to a foreign substance (or) organism”

It is generally classified into TWO categories

Active Immunity

Passive Immunity

Acquired Immunity


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Active Immunity

Natural active immunity

Artificially active immunity

Passive Immunity

Natural passive immunity

Artificially passive immunity


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Active Immunity

Natural acquired active immunityImmunity is developed by the host in response to the

antigen that enters by Natural infection.

For example, a person attacked by measles or Small pox develops natural active immunity as he recovers from the disease.

Artificially acquired active immunityImmunity is attained by the host in response to the

antigen got by Vaccination.

Vaccines are preparations of live (attenuated) or killed microorganisms (or) their products (toxoids).

Active immunity is the resistance developed by an individual in response to an antigenic stimulus.

Active immunity involves the the synthesis of specific antibodies (humoral immunity) or production of immunologically active cells (Cell mediated immunity)


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Passive Immunity

Natural acquired passive immunity

The immunity that non-immune individual acquires by receiving antibodies (or) sensitized white blood cells from another immune individual is known as “Passive immunity”

The immunity transferred from the mother to the child passively is known as “Natural acquired passive immunity”.

In human beings this natural passive immunity occurs mainly by the passage of antibodies (Immunoglobulin G) from the mother to her unborn child through the placenta during the later part of pregnancy.

Artificially acquired passive immunityTransfer of immunity from an immunized donor to a non

immune recipient by transferring antibodies (or) immunized lymphocytes is known as “Artificially passive immunity”.

It is used in the treatment of Tetanus, Diphtheria, Gas gangrene, Snake bite.


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What is Immunity? Explain the types of Immunity? (Presentation)

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