Immunity Short And Long Essays Question And Answers

Types Of Immunity

• Innate immunity
• Acquired immunity
  • Types
    • Active immunity
      • Natural active
      • Artificial active
    • Passive immunity
      • Natural passive
      • Artificial passive

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Antigens

• Heterophile Antigen
  • These are the same or closely related antigens present in different tissues of more than one species
• Haptens
  • These are substances unable to induce antibody formation on its own but can be immunogenic when linked to carrier proteins
  • Haptens is a partial/incomplete antigen

Immunoglobulin

• These are substances which are formed in serum in response to an antigen
• Immunoglobulin consists of two heavy chains and two light chains held together by disulphide bonds

Immunoglobulin Classes

Types Of Antigen-Antibody Reactions

5. Complement

• Complement refers to a system of factors which occurs in normal serum and are activated by antigen-antibody reaction
• Complement is triggered by two parallel pathway
• Classical pathway
• Alternate pathway

6. Interleukins (IL)

Hypersensitivity Reactions

8. Vaccines

Immunity

Question 1. Define and classify immunity. Discuss acquired immunity.
Answer:

Immunity Definition

1. Immunity:

• Immunity is defined as resistance exhibited by the host against any foreign antigen including micro-organisms.

Immunity Classification

• Immunity may be classified into different types as follows.

 Acquired immunity Definition

• Acquired immunity is the resistance acquired by an individual during life.

Acquired immunity Types:

1. Active Immunity:

• Active Immunity is subdivided into two types.
  • Natural Active Immunity.
    • Acquired by natural subclinical or clinical infections.
    • It is long-lasting.
    • Example: A person recovering from smallpox develop natural active immunity.
  • Artificial Active Immunity.
    • Induced by vaccination.

Active Immunity Mechanism

• Active immunity stimulates both humoral and cell-mediated immunity.

Passive Immunity

• Passive Immunity is subdivided into two types:
  • Natural
    • Immunity is transferred from mother to fetus transplacentally.
  • Artificial
    • Occurs through the parenteral administration of antibodies.

Passive Immunity Mechanism

• Passive Immunity is induced in an individual by preformed vaccines against infective agents.
• Passive Immunity is short-lasting.
• Passive Immunity is used when immunity is required immediately.

Passive Immunity Uses

• To provide immediate short-term protection
• For suppression of active immunity.
• For treatment of serious infection

 Innate immunity

Innate immunity Definition:

• Innate immunity is the resistance that individual possesses by birth.

Innate Immunity Types:

• Factors influencing it:

1. Age:

• Infants have immature immunity, while during old age there is gradual decreases in immunity.
• This increases susceptibility to infections.

2. Hormones:

• Hormonal disorders may lead to increased susceptibility to infections.

3. Nutrition:

• Malnutrition predisposes to infections.

Innate Immunity Mechanism

1. Epithelial Surfaces:

• Skin.
  • Act as a mechanical barrier to micro-organisms
  • Provides bacteriocidal secretions.
  • The resident bacterial flora prevents colonization by pathogens.
• Respiratory Tract.
  • Nasal passages arrest the inhaled particles.
  • The mucous secretions of the respiratory tract act as a trapping mechanism.
  • Cilia help to propel the particles toward the pharynx.
• Intestinal Tract.
  • Mouth – inhibits micro-organisms.
  • Acidic gastric pH – destroys bacteria.
  • Intestine – prevents colonization of bacteria,
• Conjunctiva.
  • Tears flushes away bacteria and dust particles.
  • Lysozyme present in tears has bacteriocidal actions.
• Genitourinary Tract.
  • Urine eliminates bacteria.
  • Vaginal secretions destroy pathogens.
  • Semen contains antibacterial substances.

Antibacterial Substances

• Antibacterial Substances include properdin, complement, lysozyme, beta-lysin, basic polypeptides, and interferons.

3. Cellular Factors:

• Phagocytic cells ingest pathogenic organisms and de¬stroy them.

4. Inflammation:

• Inflammation is a non-specific defense mechanism.
• Inflammation phagocytoses and destroys micro-organisms.

5. Fever:

• Stimulates production of interferon

6. Acute Phase Proteins:

• Activate alternate pathways of complement.

Types Of Active Immunity With Examples

Difference Between Active And Passive Immunity

Two Examples Of Passive Immunity

Antigen Definition

• The antigen is a substance which, when introduced into a body evokes an immune response to produce a specific antibody with which it reacts in an observable manner.

Antigen Types

1. Complete Antigen.

• These can induce antibody formation by themselves.

2. Complete Antigen.

• These can induce antibody formation by themselves.

3. Incomplete Antigen/Haptens.

• These are unable to induce antibody formation on their own.
• But can become immunogenic when they are covalently linked to carrier proteins.