Immunity

Question 1

Immunity

Answer 1

The ability of the host to fight against a disease/infection causing organism (pathogen) encountered by the immune system is termed as immunity

Question 2

Name the two types of immunity

Answer 2

1. Inborn / Innate / Gerneralised Immunity
2. Acquired Immunity

Question 3

Difference b/w vaccine and toxoid

Answer 3

Vaccine:
1. Provides lifetime immunity
2. Vaccines contain killed or attenuated disease-causing organisms

Toxoid:
1. 6 months immunity
2. Toxin is produced by the microorganism

Question 4

Artificially acquired active and passive immunity

Answer 4

Active:
Antigens are introduced in vaccines; body produces antibodies and specialised lymphocytes

Passive:
Preformed antibodies in immune serum are introduced by injection

Question 5

Blood cell formation
1. Early foetal development
2. Mid foetal development
3. Later foetal development

Answer 5

1. mesenchyme of yolk sac
2. liver and spleen
3. bone marrow

Question 6

Bone marrow function

Answer 6

1. Gives rise to all lymphoid cells
2. Maturation and proliferation of B-cells (B-Lymphocytes)

Question 7

Thymus function

Answer 7

1. Major action of thymus occurs during childhood
2. Maturation and differentiation of T-cells (T-Lymphocytes)

Question 8

Lymph nodes function

Answer 8

1. Non-specific filtration of particulate matter
2. Proliferation of B and T lymphocytes

Question 9

Spleen function

Answer 9

1. B-cells and T-cells multiply
2. Removal of debris, particulate matter and aged/defective RBC- MALT, NALT, GALT, BALT

MALT: Mucosal Associated Lymphoid Tissue
NALT: Nasal
GALT: Gut
BALT: Bronchiole

Question 10

Phagocytosis

Answer 10

Phagocytosis is a non-specific response. It is the process of engulfment and destruction of particles such as bacteria, allergens etc. by specific cells like macrophages and neutrophils

Question 11

Inflammation

Answer 11

Inflammation is a protective and non-specific immune response which is elicited due to a tissue injury. Inflammation can be localised or systemic.

Question 12

Inflammation- steps

Answer 12

1. Tissue injury
2. Swelling: Vasodilation of the capillaries around the area of tissue damage
3. Redness: Increased amount of blood flow in the area
4. Heat: Temperature raises locally in that specific region
5. Pain: Permeability of the capillaries result in the escape of plasma into the surrounding region
6. Plasma contains phagocytic cells, antibodies, and bactericidal agent
7. Destruction of antigens and healing of tissue

Question 13

Difference b/w B-cells and T-cells

Answer 13

B cells
1. maturation and differentiation in bone marrow
2. accounts for humoral immune response

T cells
1. maturation and differentiation in thymus
2. accounts for cell-mediated immune response

Question 14

APCs

Answer 14

Antigen Presenting Cells
Macrophages and neutrophils
Destroy antigens by phagocytosis, non-specific immune response

Question 15

Interferons

Answer 15

1. Anti-viral in action
2. Specific in nature
3. Signaling proteins released by virus infected cells
4. Interfere with viral replication
5. Signal the neighbouring cells to increase their anti-viral defenses

Examples:
IFN-alpha and IFN-beta are secreted by virus infected cells
IFN-gamma is secreted by T-cells, NK cells and Macrophages

Question 16

Antigens

Answer 16

1. Foreign molecule that can trigger the immune system of the host organism in producing an antibody
2. Most anitgens are either proteins or polysaccharides
3. Lipids and nucleic acids become antigenic only when they combine with a protein or polysaccharide

Question 17

Haptens

Answer 17

These are small molecules that can elicit an immune response only when attahed to a large, carrier molecule, like a protein

Question 18

Antibodies

Answer 18

1. Proteins (Gamma globulins)
2. Specific in function
3. Released by Plasma cells (B-cell)
4. Forms Ag-Ab complex to facilitate the destruction of antigen

Question 19

Effector mechanisms

Answer 19

1. Agglutination
2. Opsonisation
3. Complement (specialised plasma proteins) mediated cell lysis

Question 20

Number of binding sites in IgG, IgM, IgA, IgD, IgE

Answer 20

IgG, IgD, IgE: monomers–> 2 binding sites
IgM: pentamer–> 10 binding sites
IgA: dimer–> 4 binding sites

Question 21

Percentage of total antibody in serum
IgG, IgM, IgA, IgD, IgE

Answer 21

IgG: 80%
IgM: 6%
IgA: 13% (monomer)
IgD: <1%
IgE: <1%

Question 22

Fc receptor binds where in IgG and IgE

Answer 22

IgG- phagocytes
IgE- mast cells and basophils

Question 23

Function of IgG

Answer 23

1. Neutralization
2. Agglutination
3. Complement activation
4. Opsonization
5. Antibody-dependent cell-mediated cytotoxicity

Question 24

Function of IgM

Answer 24

1. Neutralization
2. Agglutination
3. Complement activation
4. The monomer form serves as the B-receptor

Question 25

Function of IgA

Answer 25

Secretory antibody 1. Neutralization 2. Trapping of pathogens in mucus 3. Present in tears, saliva, and colostrum

Question 26

Function of IgD

Answer 26

B-cell receptor Active against parasitic infections

Question 27

Function of IgE

Answer 27

Activation of basophils and mast cells against parasites and allergens

Question 28

Allergy

Answer 28

An oversensitive reaction by the immune system against a foreign particle (Allergen)

Question 29

Clinical manifestations of an allergy

Answer 29

1. Itching 2. Swelling 3. Redness 4. Typical wheal and flare reaction on the skin

Question 30

Treatment for allergic reaction

Answer 30

Administering anti-histamine drugs

Question 31

Autoimmunity

Answer 31

1. The condition where an individual produces antibodies against one's own antigens 2. The body loses its ability to differentiate between self and non-self antigens

Question 32

Disease when there is autoimmune disorder related to 1. RBC antigen 2. Muscle antigen 3. Thyroid antigen 4. Antigens in joins

Answer 32

1. Chronic anaemia 2. Myasthenia gravis 3. Hashimotto's disease 4. Rheumatoid arthritis

Question 33

Immunodeficiency disorders

Answer 33

1. SCID- Severe Combined Immuno-deficiency- T and B cells absent: congenital 2. Di George's Syndrome- lack of T-cells 3. Agammaglobulinemia- lack of B-cells 4. AIDS: Acquired Immunodeficiency Syndrome