Overview of immune system

Question 1

Define Immune system

Answer 1

a complex system imp for:

1) distinguishing between self and non self
2) protecting body from foreign substances

Question 2

Good Roles of the Immune System

Answer 2

• Defence against infections
• Defence against tumours
• clearance of cells and Tissue repair

Question 3

“Foe” roles of the immune system

Answer 3

• injure cells + inducen pathogen inflammation

- rejects tissue grafts + newly introduced proteins

Question 4

The immune response sequence

Answer 4

Recognition–> activation (processing) –> elimination

Question 5

Biological roles of “innate” immunity

Answer 5

• deals with mild infections
• first phase for more serious infections
• initiates adaptive response

Question 6

Biological roles of Adaptive Immunity

Answer 6

• specificity
• deals with stronger + more intense infections
• stronger exposure after exposure to the same antigen (memory)

Question 7

Difference in response time between the two systems

Answer 7

Innate -> no time delay

adaptive -> delay (5-10days)

Question 8

difference in diversity between the two systems

Answer 8

innate -> recognises larger, common features

adaptive -> recognises unique part of microbes

Question 9

difference in receptor genes between the two systems

Answer 9

innate -> encoded in our genome

adaptive -> V(D)J recombination (clone-specific)

Question 10

difference in Ligand between the two systems?

Answer 10

innate -> PAMPS (pathogen associated molecular patterns)

adaptive -> antigen (specifically Epitope)

Question 11

difference in Memory between the two systems?

Answer 11

innate -> NO memory (same response after a repeated exposure)

adaptive -> memory (more intense response after repeated exposure)

Question 12

Cellular components of Innate Immunity

Answer 12

Cellular:

• PHAGOCYTES:
• granulocytes
• monocytes
• macrophages
• dendritic cells

-NATURAL KILLER CELLS

Question 13

Humoral components of Innate Immunity

Answer 13

• Complement system
• cytokines
• Antimicrobial peptides

Question 14

Cellular components of Adaptive Immunity

Answer 14

Lymphocytes

Question 15

Humoral components of Adaptive Immunity

Answer 15

• Antibodies

- cytokines released by lymphocytes

Question 16

Types of Leukocytes in the peripheral blood?

Answer 16

Granulocytes:

• Neutrophils (65%)
• Eosinophils (2-4%)
• Basophils (1%)

Lymphocytes

monocytes (4-8%)

Question 17

Steps in leukocyte migration?

Answer 17

1) Rolling
2) Tight Binding
3) Diapedesis
4) Migration

Question 18

Rolling

Answer 18

• Rolling of cell on the endothelium
• Mediated by SELECTINS.
• Ligands: Carbohydrates

E-selectins -> on the endothelium
L-selectins -> on the leukocytes
P-selectins -> on the platlets + endothelial cells

Question 19

Tight Binding

Answer 19

• mediated by INTEGRINS (found on the effector cell)
• Integrins –> Heterodimer (alpha and beta subunit)*
• Ligand: peptides (ICAM)
• conformational change occurs, increasing the strength of the binding, so stabilises the leukocyte.

Question 20

Diapedesis

Answer 20

• This is the transendothelial transport

- also INTEGRIN mediated

Question 21

Migration

Answer 21

Movement of Leukocyte to infection site.

• mediated by 1) chemokines 2) chemoattractants (microbial derived peptides)
• GPCR involved

Question 22

Effector responses of the leukocytes

Answer 22

Neutrophils:
-Phagocytosis + killing

Helper T - cell:
- production of cytokines

Cytotoxic T-Cell:
-cytotoxicity