17. Innate and Adaptive Immunity

Question 1

What are humans and pathogens both made of, and why does that mean pathogens needs non self markers?

Answer 1

Proteins, carbohydrates and lipids. As they’re both made of the same things, the immune system needs another way of differentiating between them, hence non-self.

Question 2

What is the difference between pathogens and the host that allow the host’s immune system to tell them apart?

Answer 2

The different proteins that allow the host and pathogen to survive and their respective niches.

Question 3

What is damage to the host a result of?

Answer 3

The pathogen breaking through the barriers to gain access to the host.

Question 4

What is an alert in the host a result of?

Answer 4

The damage caused to the barrier which allows entry of the pathogen.

Question 5

What is the first barrier to infection?

Answer 5

Epithelia.

Question 6

What type of epithelia is found at the following sites?

a. Blood vessel
b. Mesothelium
c. Trachea
d. Renal collecting tubule
e. Oviduct
f. Salivary gland duct
g. Skin
h. Vagina
i. Bladder
j. Gall bladder

Answer 6

a. Simple squamous
b. Simple squamous
c. Pseudostratified ciliated
d. Simple cuboidal
e. Simple columnar ciliated
f. Stratified cuboidal
g. Stratified squamous keratinised
h. Stratified squamous non-keratinised
i. Transitional
j. Simple columnar

Question 7

How do epithelial cells act as a defence?

Answer 7

They form a selectively permeable barrier between outside and inside the host. They produce natural antibodies, possess motile cilia to keep the surface free of bacteria, they’re rapidly renewable, they produce cytokines, chemokines (attract other cells) and mucins.

Question 8

How does damage to endothelium trigger the innate and adaptive immune response?

Answer 8

The damage pathogens cause to the epithelia trying to break through activates the epithelia. The epithelial releases cytokines which permeabilise the endothelium so cell and fluid migrate. There is oponisation so it is phagocytosed more regularly. Phagocytosis raises an immune response.

Question 9

What two responses do inflammatory mediators cause?

Answer 9

Increased permeability so fluid leakage from blood vessels allows antibodies to be released at the site of the infection.
Migration of macrophages, neutrophils and lymphocytes into the tissue so microbicidal activity is increased.

Question 10

What five things happen in inflammation as an immunological response?

Answer 10

Calor, tumor, rubor, dolor and functio laesa.

Heat, swelling, redness, pain and loss of function.

Question 11

Who championed cell-mediated immunity and when?

Answer 11

Elie Metchnikoff in 1893.

Question 12

Who championed humour all immunity and when?

Answer 12

Paul Ehrlich in 1900.

Question 13

Who saw the link between cell mediated and humour all immunity and when?

Answer 13

Sir Almroth Wright in the early 1900s.

Question 14

What are three main roles of the innate immune response?

Answer 14

Inbuilt immunity to resist infection.
Native, natural immunity (from birth, not specific, not enhanced by second exposure, no memory, cellular and humour all components, poorly effective without adaptive immunity).
Involved in triggering and amplifying adaptive immune response.

Question 15

Discuss the key features of adaptive immunity.

Answer 15

Established to adapt to infection. It’s learnt from experience, confers pathogen-specific immunity, enhanced by a second exposure, has memory, uses cellular and humoural components, is poorly effective without innate immunity.

Question 16

What is a distinction between less and more elaborate organisms in terms of their immune responses?

Answer 16

More developed organisms have an innate and adaptive immune response working together, less developed organisms just have an innate response.

Question 17

What cells are involved in innate immunity? Give a function for each.

Answer 17

Macrophages - phagocytosis
Monocytes - presentation to lymphocytes
Neutrophil - phagocytosis
PMN - anti-bacterial
Eosinophil - anti-parasite and cause allergies
Basophil - may help in protecting mucosal surfaces and cause allergies
Mast cell - protection of mucosal surfaces and cause allergies
Natural killer cells.

Question 18

Which innate immunity cell looks very red under the microscope?

Answer 18

Eosinophil.

Question 19

What are pathogens?

Answer 19

Disease-causing organisms.

Question 20

What are phagocytes?

Answer 20

Cells able to engulf and density bacteria, extracellular viruses and immune complexes.

Question 21

What is phagocytosis?

Answer 21

Active engulfment of particles into a phagosome.

Question 22

What do patients with neutrophil deficiencies suffer from?

Answer 22

Recurrent infections.

Question 23

What is the role of macrophages?

Answer 23

Phagocytose microbial cells or damage/unwanted cells. They release cytokines for innate and adaptive immunity. They act as professional nation presenting cells in adaptive immunity.

Question 24

What is opsonisation?

Answer 24

The coating of a microorganism by antibodies or complement to render it recognisable as foreign by phagocytes, thus enhancing phagocytosis.

Question 25

What is the role of natural killer cells?

Answer 25

Part of the innate immune system, they recognise and kill abnormal cells, like tumour cells. They induce apoptosis in virus infected cells by pumping proteases through pores that they make in target cells.

Question 26

What do people with natural killer cell deficiency suffer from?

Answer 26

Persistent viral infections.

Question 27

Give the function of the following humoural components:

a. Transferrin and lactoferrin
b. Interferon
c. Lysozyme
d. Fibronectin
e. Complement
f. TNF-alpha

Answer 27

a. Deprive micro organisms of iron
b. Inhibit viral replication and activates other cells which kill pathogens
c. Breaks down bacterial cell wall of some gram positive bacteria
d. Coats bacteria and promotes their rapid phagocytosis
e. Components and their products cause destruction of microorganism directly or with the help of phagocytise cells
f. Suppressed viral replication and activates phagocytosis.

Question 28

How is a pore in the pathogen membrane made?

Answer 28

C5b binds C6 and C7. C5b,6,7 complexes bind to the membrane via C7. C8 binds to the complex and inserts into the cell membrane. C9 molecules binds to the complex and polymerise. 10-16 molecules of C9 bind to form a pore in the membrane.

Question 29

What can a deficiency in the following complement molecules lead to?

a. C1, C2 or C4
b. C3
c. C5-C9

Answer 29

a. Immune complex disease (type III)
b. Recurrent bacterial infections, pneumonia etc.
c. Recurrent Neisserial infections, N. meningitidis and N. gonorrhoeae.

Question 30

Where do the T and B cells develop?

Answer 30

T - thymus

B - bone marrow

Question 31

What happens when T and B cells are activated?

Answer 31

T cells become T helper cells that activate B cells, or cytotoxic T lymphocytes.
B cells become plasma cells that produce antibodies.

Question 32

What are the three main ways in which an antibody protects the host from infection?

Answer 32

Neutralisation - prevents bacterial adherence to the host’s cells.
Opsonisation - antibody promotes phagocytosis.
Complement activation - activates complement, which enhances opsonisation and loses some bacteria.

Question 33

How does clonal selection solve the problem associated with clonal distribution?

Answer 33

Clonal selection raises the clonal frequency of cells with a particular antigen specificity rather than all cells. This means the particular lymphocytes have a high enough frequency to mount an effective response.

Question 34

What are the five phases of an adaptive immune response?

Answer 34

Recognition phase - clonal selection and expansion
Activation phase - differentiation to effector cells
Effector phase - humoural and cell-mediated immunity, elimination of antigen
Decline homeostasis - T and B cell apoptosis
Memory - seeding of T and B cell memory.