CMB1003/L26 Immune System in Action

Question 1

Describe the 4 stages of immune response during an infection.

Answer 1

Local infection & penetration of epithelium
Local infection of tissues
Lymphatic spread
Adaptive immunity

Question 2

What occurs during local infection and penetration of epithelium? (2)

Answer 2

Wound healing induced
Antimicrobial proteins and peptides, phagocytes, and complement destroy invading microorganisms

Question 3

What occurs during local infection of tissues? (4)

Answer 3

Complement activation
Dendritic cells migrate to lymph nodes
Phagocyte action
NK cells activated
Cytokines and chemokines produced

Question 4

What occurs during lymphatic spread? (2)

Answer 4

Pathogens trapped and phagocytosed in lymphoid tissue
Adaptive immunity initiated by migrating dendritic cells

Question 5

What occurs during adaptive immunity? (2)

Answer 5

Infection cleared by specific antibody
T-cell-dependent macrophage activation and cytotoxic T cells

Question 6

Give 3 extracellular sites of infection.

Answer 6

Interstitial spaces
Blood
Lymph

Question 7

Give 2 intracellular sites of infection.

Answer 7

Cytoplasmic
Vesicular

Question 8

By which 2 mechanisms are symptoms of disease caused?

Answer 8

Direct effects of pathogens
Indirectly by immune responses

Question 9

Give 3 examples of immune response.

Answer 9

Infectious agent
Immunodeficiency
Immunopathology
Hypersensitivity - allergy/ autoimmunity

Question 10

Which pathogen is leprosy caused by?

Answer 10

Mycobacterium leprae

Question 11

Describe tuberculoid leprosy. (3)

Answer 11

Organisms present at low to undetectable levels
Low infectivity
Granulomas and local inflammation
Peripheral nerve damage
Normal serum immunoglobulin levels
Normal T-cell responsiveness
Specific response to M. leprae antigens

Question 12

Describe lepromatous leprosy. (3)

Answer 12

Organisms show florid growth in macrophages
High infectivity
Disseminated infection
Bone, cartilage and diffuse nerve damage
Hypergammaglobulinemia
Low or absent T-cell responsiveness
No response to M. leprae antigens

Question 13

Which kind of leprosy activates more T(H)1 cytokines?

Answer 13

Tuberculoid

Question 14

Which kind of leprosy activates more T(H)2 cytokines?

Answer 14

Lepromatous

Question 15

Give 2 causes of secondary immunodeficiency.

Answer 15

Malnutrition
Lymphoproliferative disease
Immunosuppressive or cytotoxic drugs
Infection
Stress

Question 16

Which kind of Ig is involved in allergy?

Answer 16

IgE

Question 17

Give an example of type II sensitivity.

Answer 17

Erythroblastosis fetalis (RBC destruction)

Question 18

Give an example of type III sensitivity.

Answer 18

Systemic lupus erythematosus (SLE)
Autoantibodies to DNA and other Ags
Immune complexes form
Deposited at susceptible sites

Question 19

Give an example of type IV hypersensitivity.

Answer 19

Type I diabetes

Question 20

Describe the pathogenesis of type I diabetes. (2)

Answer 20

Effector T cell recognises peptides from a B-cell specific protein and kills B cells
Glucagon and somatostatin still produced by a and y cells but no insulin made

Question 21

What causes autoimmune diseases? (2)

Answer 21

Loss of self tolerance
Increasing frequencies in Western cultures
Sex hormones

Question 22

What is the mechanism of disease in rheumatoid arthritis?

Answer 22

Autoreactive T cells and autoantibodies against antigens localised to joint synovium

Question 23

What is the mechanism of disease in systemic lupus erythematosus?

Answer 23

Autoantibodies and autoreactive T cells against DNA, chromatin proteins, and ubiquitous ribonucleoprotein antigens

Question 24

Give 3 potential treatments for autoimmune disease.

Answer 24

Vaccines
Immunotherapy
Monoclonal antibodies

Question 25

How does immunotherapy work? (3)

Answer 25

Antibodies used to bind to tumours of cytokines induce specific killing
Antibodies/drugs release immune system blocks that cancer cells produce
Inhibits negative immune regulation