Immunity Lecture

Question 1

What is the purpose of immune system?

Answer 1

For survival and protection against infections

Question 2

What is the innate immunity?

Answer 2

Natural or native
First line of defense
Always present

Question 3

What are macrophages?

Answer 3

Evolve from monocytes formed in bone marrow
“circulating scavengers”
When monocytes differentiate and move to the tissue
Found in inflammation sites

Question 4

What are natural killer cells?

Answer 4

“Large granular lymphcytes”
Part of innate immunity
Kills infected cells, tumor cells and possibly normal cell

Question 5

What is the adaptive immunity?

Answer 5

Acquired or specific
Silent but adapts when required
Recognizes microbes and non-microbial substances
"Immune response"
Humoral or Cellular

Question 6

What does the humoral adaptive immunity include?

Answer 6

B lymphocytes, antibodies, extracellular microbes

Question 7

What does the cellular adaptive immunity include?

Answer 7

T lymphocytes, intracellular microbes

Question 8

Mechanism of killing an infected cell?

Answer 8

Antibody secretion –> activation of macrophages –> inflammation –> stimulation of B cells –> killing of infected cell

Question 9

What are dendritic cells?

Answer 9

Antigen presenting cells
Under epithelia –> at the site of entry of microbes
Capture microbial antigen and migrate to lymph node

Question 10

What are lymphocytes?

Answer 10

T lymphocytes (mature in thymus)
B lymphocytes (mature in the bone marrow)
Naive concentrated in lymphoid organs
Each cell expresses receptors for a single antigen

Question 11

What are T cells?

Answer 11

Majority in blood
Do not recognize circulating antigens
Recognize antigen peptide fragments bound to MHC
Cytotoxic, helper, and suppressor T cells

Question 12

What are CD4 cells?

Answer 12

MHC Class II -- Helper 
For internalized extracellular antigens
B cell- helps antibody production 
Macrophage- helps in phagocytosis
Activates T cells and NK cells

Question 13

HIV destroys what?

Answer 13

Helper T cells

Question 14

What are CD8 cells?

Answer 14

For cytoplasmic antigens (viruses)
Direct killing of virus infected cells/tumor cells
Cytotoxic T cells

Question 15

What does a unique antigenic profile mean?

Answer 15

Unique combination of HLA alleles (HLC haplotype)

Inheritance of HLA genes could be responsible for diseases and allergies

Question 16

What are TH1 molecules?

Answer 16

Produce IFN-gamma
Induce IFN-gamma and IL-2
Trigger macrophage and IgG
Defend against intracellular microbes
Role: immune-mediated chronic inflammation

Question 17

What are TH2 molecules?

Answer 17

Produce IL-4/5/13
Induce IL-4
Trigger IgE, mast cells, eosinophils
Defend against helminthic parasites
Role: Allergies

Question 18

What are TH17 molecules?

Answer 18

Produce IL-17 IL-22 and chemokines
Induce TGF-beta, IL-6/1/23
Trigger the recruitment of neutrophils and monocytes
Defend against extracellular bacteria and fungi
Role: immune-mediated chronic inflammation

Question 19

How are B cell activated?

Answer 19

Naive B cells recognize antigens and under the influence of TH cells and other stiuli, the B cell are activated to proliferate and to differentiate into antibody-secreting plasma cells and some become memory cells

Question 20

What are suppressor T cells?

Answer 20

Turns off the immune response when antigen has been eliminated

Question 21

When antigens are eliminated what happens?

Answer 21

Effecto lymphcytes die by apoptosis
Long live memory cells remain
Subsequent exposure to antigens will lead to a faster response due to memory cells (vaccination)