SFBH S5

Question 1

Identify components of the third line of defence

Answer 1

antibodies, T cells, B cells,

Question 2

Give a description of Antibodies.

Answer 2

• Immunoglobins
• Proteins found in blood plasma and other body fluids
• Produced in the lymph nodes by B cells in response to specific antigen
• Can combine with and help neutralise an antigen
• Highly specific for antigen that stimulated their synthesis and release
• Antigen-antibody response
 Activates production of proteins that result in bacteria being ingested and destroyed  histamine released  inflammation

Question 3

Give a description of T cells

Answer 3

• Lymphocytes
• Form in bone marrow/thymus gland
• Remain inactive in blood and lymph until they meet antigen
• Cell mediated immunity: Antigen binds to T cell  activating it to multiply  destroy
• Some memory T-cells remain in body as memory cells so know how to fight off antigen next time introduced
• Do not produce antibodies

Question 4

Give a description of B Cells

Answer 4

• Mature and develop in bone marrow of humans
• Control the humoral blood response  B cells in blood and lymph activated by antigens
• Produced in response to helper T-activation or by the presence of antigens
• Activated B cells  clone themselves and then differentiate…
 Into plasma cells that send antibodies into the blood
 OR into memory cells
(Process occurs in lymph nodes)

Question 5

Describe the immune response in the human body in terms of the interaction between B and T lymphocytes.

Answer 5

• T cells help and influence B cells
• B and T lymphocytes interact as both attacking same antigen
• Helper T cells stimulate B and T cells to clone
• When antigen enters body
o Processed by macrophage  places fragments of antigen on external membrane
o Fragments recognised by helper T cells and B cells
o Signal to other cells to initiate immune response

Question 6

Detail Mechanism 1 that allows interaction between B and T lymphocytes

Answer 6

o T cell produces soluble factor after interaction with antigen
o B cell reacts with soluble factor and specific antigen  becomes functional antibody-producing cell

Question 7

Detail Mechanism 2 that allows interaction between B and T lymphocytes

Answer 7

o Contact between T and B cell  because of interaction with antigen
o Contact allows T cell to signal the B cell to become functional antibody-producing cell
• Helper T cells  T lymphocytes that help B lymphocytes
• Work together - T cell will recognise antigen and attack with B cell

Question 8

Name the range of T lymphocytes

Answer 8

Killer T cells, Helper T cells, Suppressor T Cells, Memory T Cells

Question 9

Whats the role of the killer T cells?

Answer 9

• Secrete substances
 Directly destroys antigens
 Enhance activity of macrophages
 Inhibit replication of viruses
• Destroy any abnormal cells e.g. cancer cells
• Produce interferon  protects cells living around infected cell from viral invasion

Question 10

Whats the role of the Helper T cells?

Answer 10

• Secrete chemicals called interleukins
 Help B cells produce antibodies
 Help formation of cytotoxic T cells
 Enhance inflammatory response

Question 11

Whats the role of the suppressor T cells?

Answer 11

• Turn off immune response after infection controlled
 Reduce release of antibodies from plasma cells
 Reduce release of chemicals from cytoxic cells

Question 12

Whats the role of the memory T cells?

Answer 12

• Recognise original invading antigen  invasion dealt with quickly
• Stimulate helper T cells  quickly producing large amount of antibodies
• Remain in lymph nodes or blood circulation  allow long-term immunity

Question 13

How do vaccination help prevent infection?

Answer 13

• Vaccination: injecting or ingesting antigens from living, dead, weakened or non-virulent strains of micro-organisms
• Stimulate a person’s immune system to develop resistance
• Exposure to same antigen  antibody-antigen response  antigen destroyed
• Some offer life-long immunity or short term
• Booster injections may be given at various intervals

Question 14

What is Active immunization?

Answer 14

o Injection of an antigen
o Stimulates production of antibodies and T and B memory cells specific to that antigen
o Protect against measles, polio and diphtheria

Question 15

What is passive immunisation?

Answer 15

o Injection of antibodies produced by other organism in response to infection
o Short term protection
o Risk: stimulating aggressive response
o Helpful for immediate protection: people have no immunity to disease they have

Question 16

The vaccination program for small pox was?

Answer 16

Effective
• Virus
• Airborne or spread by direct contact
• 1796: Edward Jenner developed vaccine  not effective
 No one realised potential
• 1840’s: vaccine became free  not widely used until became compulsory
• 1967: WHO developed worldwide immunisation program  extremely successful
• 1979: WHO  vaccination eradicated disease
• Only remaining samples of virus in laboratories

Question 17

The vaccination program for Diphtheria was?

Answer 17

Ineffective,
• Bacterial infection
• Transmission  physical or respiratory contact
• Vaccination DTP (prevents against Diphtheria, Tetanus and Pertussis (whooping cough)
• 1923: vaccine released
• 1940s-50s: decrease in occurrence
• 1974: WHO’s EPI program  aim to immunise all children against disease (diphtheria, polio) by 1990
• 2002: 5000 death  4000 under 5
• 2005: Vaccination rate 95% across 183 countries

Question 18

The vaccination program for Polio was?

Answer 18

Effective,
• Virus
• Transmission  inhaling infected droplets or direct contact
• 1955: first vaccine developed  effective to some extent  years following – 200 people developed disease and 11 died
• 1960’s: safer vaccine developed  decreased spread and occurrence by 60-70% (very effective)
• 1974: WHO’s EPI program  became scarce in industrialised nations
• 1988: World Health Assembly – Global Polio Eradication Initiative  widespread vaccination of children

Question 19

Why do we suppress the immune response when doing organ transplants?

Answer 19

• Transplant organs stimulates immune response  tissue proteins of one person not the same as another (except for twins or closely inbred strains)
• Before transplant  donor and recipient very closely matched to have similar major histocompatibility complexes (MHC’s) – hundreds so hard to match
• Body identifies as foreign
• T cells  main cell responsible for rejection of transplanted organs
• Patients given powerful immunosuppressive drugs  suppress immune response in order to help transplanted organ live and become apart of body
• Side effects: Diabetes, renal impairment, susceptibility to infection

Question 20

What did Macfarlane Burnet do?

Answer 20

Contribution to understanding of immunological responses

• One of the founders of immunology
• Isolated strains of viruses to develop vaccines
• Investigated how the immune response functions