Introduction

Question 1

Which cells link the innate and adaptive immune systems by presenting antigens to T cells?

Answer 1

Dendritic cells

Question 2

What are the professional antigen presenting cells?

Answer 2

macrophages, dendritic cells and b cells (all present antigen to T cells to initiate immune response)

Question 3

What is immunity?

Answer 3

Defense of the host against foreign pathogens (antigens)

Question 4

What are the 3 categories of host defense?

Answer 4

Physical & chemical barriers
Cells of innate immune system
Cells of adaptive immune system

Question 5

What are the chemical barriers against infection?

Answer 5

• Tears
• Sweat
• Mucus
• Stomach acid
• Antibodies
• Antimicrobial peptides

Question 6

What are physical barriers against infection?

Answer 6

Skin
Mucosal surfaces- upper and lower respiratory tract, intestinal epithelium, vaginal epithelium

Question 7

What cells are considered granulocytes?

Answer 7

neutrophils, basophils, eosinophils and mast cells (although mast cells are not involved in granulocytosis)

Question 8

What are the key cells of the innate immune system?

Answer 8

macrophages- monocytes
dendritic cells
granulocytes
natural killer cells

Question 9

What are the tissue-specific macrophages?

Answer 9

• Alveolar and Peritoneal macrophages
• Kuppfer cells
• Osteoclast
• Microglial in brain
• Histiocytes

Question 10

What are monocytes?

Answer 10

a monocyte is a circulating precursor of
macrophages in blood
they leave bloodstream and become more specialised and mature into macrophages

Question 11

Describe macrophages

Answer 11

Phagocytosis and killing of microorganisms
Activation of T cells and initiation of the immune
response (they are a professional antigen presenting cell meaning they present antigen to T cell to activate them and induce immune response (adaptive))

Question 12

What are the functions of neutrophils?

Answer 12

phagocytosis
degranulation- granules can be expelled to kill other cells when invaded
involved in neutrophil extracellular traps (NETs)

Question 13

Discuss neutrophils structure etc.

Answer 13

they are polymorphonuclear
they are a granulocyte
Short life span (hours)
Very important at “clearing” bacterial infections

Question 14

What links the innate and adaptive immune systems?

Answer 14

the immune system acts in synergy to fight infections
T cells and apc interactions link innate and adaptive immune response
There is close synergy between the two systems with the adaptive response greatly improving the efficiency of
the innate response and the innate response setting the scene for activation of the adaptive response

Question 15

Discuss granulocytes other than neutrophils

Answer 15

eosinophils and mast cells - found in tissues
basophil - found in circulation
all play a role in allergic inflammation and destruction of parasites via degranulation
eosinophils- produce antihistamines and have a double-lobed nucleus

Question 16

Discuss dendritic cells

Answer 16

found in lymphoid tissue
they are professional antigen presenting cells
specialised dendritic cells called Langerhan cells are in the epidermis of skin
initiate adaptive immunity through activation of T cells
dendritic cells are the most potent stimulators of T cells (most common)

Question 17

What cells have characteristics/functions of innate and adaptive immunity so can’t be classed as one or the other?

Answer 17

Gamma-delta T cells
Innate lymphoid cells
Natural killer T cells

Question 18

What are the cells of the adaptive immune response?

Answer 18

Lymphocytes- b cells and t cells
B cells produce antibodies and are also professional antigen presenting cells
There are helper T cells and cytotoxic T cells (natural killer T cells?)
there are memory B and T cells - produced by immune response, they reside and are long-term and are reactivated when infected by same pathogen
there are regulatory b and t cells

Question 19

Discuss T-lymphocytes

Answer 19

Helper T cells are involved in macrophage enhancement and b cell activation
Cytotoxic T cells release toxic granules to kill infected cells - affect tumour cells and cause apoptosis

Question 20

Discuss B-lymphocytes

Answer 20

there are memory cells which are long-lived and have an enhanced response to future infection
there are plasma cells which are short-lived and provide immediate protection by secreting large amounts of antibodies that immobilise the pathogen (they stick to pathogen to make it visible to cytotoxic T cell which kills them)

Question 21

Discuss immunoglobulin and epitope

Answer 21

immunoglobulin is usually attached to b cell receptor
epitope is attached to antigen
epitope specificity is important for specific immune response

Question 22

What is the difference between lymphocytes and leukocytes?

Answer 22

Both of white blood cells but only lymphocytes are b and t cells

Question 23

Discuss immune system

Answer 23

If immune system cannot go back to homeostasis(normal) then this can cause chronic inflammation, hypersensitivity, immunodeficiencies and immunosuppression
Immunosuppression is a drop in the response of the immune system to infection. Immunodeficiency is a lack in the immune response of the body to an infection