Chapter 8 - Types And Deficiencies

Question 1

Acquiring specific immunity

1. Define acquired immunity
2. Define specific immunity
3. Active immunity
   • active natural
   • active artificial
4. Passive immunity
   • passive natural
   • passive artificial

Answer 1

1. A resistance to specific pathogens acquired over the lifetime of an organism.
2. Immunity based on specific antibodies.
3. Active immunity = antibodies are produced in the person’s own body.
   • active natural = antigens enter the body naturally.
   • active artificial = antigen is introduced into the body as a vaccine.
4. Passive immunity = antibodies from another organism enters the person’s body.
   • passive natural = antibodies enter a person naturally from the mother to the foetus via the placenta or her milk.
   • passive artificial = antibodies are introduced into the body by injection (e.g. anti-venom)

Question 2

Vaccination

1. Purpose/use?
2. Attenuated vaccine
3. Inactivated (or killed vaccine)

Answer 2

1. To activate the immune system to produce antibodies against specific disease-causing organisms.
2. Vaccine consisting of a weakened form of the disease-causing agent.
3. Vaccine consisting of a component of the disease-causing agent, enough to cause a response, can be genetically engineered.

Question 3

Herd immunity

1. Define
2. High herd immunity effect

Answer 3

1. When the vaccination of greater than 90% of a population provides some protection for individuals who have not developed immunity.
2. Makes it difficult for the disease the spread because there are less hosts to infect.

Question 4

Defects in the immune system

1. Exaggerated response to malfunction
2. Suppressed response to malfunction

Answer 4

1. Autoimmune diseases, allergies.
2. AIDS, SCID, no T and B cells, inherited.

• AIDS = acquired immunodeficiency syndrome
• SCID = severed combined immunodeficiency

Question 5

Autoimmune diseases

1. What are they?
2. What occurs?

Answer 5

1. Impaired ability of the immune system to recognise certain cells or tissue types as self.
2. T cells attack tissues directly and plasma cells indirectly secrete antibodies. The body produces autoantibodies - antibodies that attack the body’s own cells.

Question 6

Autoimmune diseases: process of multiple sclerosis (MS)

Answer 6

1. T cells incorrectly recognise the myelin sheath around nerve fibres in the brain and spinal cord as a foreign antigen and attack it.
2. T cells release cytokines, causing inflammation.
3. Inflammation recruits more immune cells (e.g. T cells, B cells, macrophages) to the site, causing more damage to the myelin.
4. Destruction of the myelin disrupts transmission of electrical impulses and leads to neural impairment. Once damaged, unprotected axon can become scarred and damaged by continual immune system attack.

• symptoms: numbness, lack of coordination, slurred speech, fatigue.

Question 7

Autoimmune diseases: process of allergic reactions

Treatments for allergic reactions:

1. Immunotherapy
2. Antihistamines

Answer 7

Process

1. Initial exposure: a new allergen encounter causes plasma cells to produce immunoglobulin (IgE) antibodies. IgE antibodies bind to the surface of mast cells where they remain. No allergic symptoms.
2. Re-exposure: the allergic bind to specific IgE antibodies in the mast cell. Several chemicals, including histamine, are released from the mast cell.
3. Hypersensitivity - immune response overreacts to antigens that post no threat to the body.

Treatments:

1. Immunotherapy: repeated tiny injections of an allergen causes an increase in circulating levels of IgG. These IgG begin to bind to the allergen before they can bind to an IgE on a mast cell, thus preventing an allergic reaction.
2. Antihistamines: drugs that inhibit the action of histamine in the body by blocking the receptors of histamine.

Question 8

Suppression of immune system: HIV/AIDS

1. HIV does?
2. Transmitted how?
3. Process

• no cure

Answer 8

1. HIV (human immunodeficiency virus) infects lymphocyte cell’s, eventually causing AIDS; HIV virus carries its genetic information in the form of two fragments of single stranded RNA.
2. Transmitted through direct contact with body fluids - sexual inter course, blood-to-blood contact, woman to foetus.
3. Process:
   • HIV binds to specific CD4 receptors on T helper cells. HIV fuses with the plasma membrane of the T helper cell. It’s RNA enters the cell.
   • HIV hijacks the T helper cells to replicate itself. Reverse transcriptase produces double stranded DNA from the viral DNA. The host cell transcribes the viral gene to produce new viruses.
   • New HIV particles bud from the host T helper cell, then infect more T helper cells. Each new virus becomes coated with some of the plasma membrane of the T helper cell, which forms an envelope around the virus.
   • T helper cell destruction recruits more T cells, accelerating infection of new cells. T helper cell population becomes depleted which impairs the immune system’s ability to function.

Question 9

Monoclonal antibodies (MAbs): cancer

1. Define monoclonal antibodies
2. Ways monoclonal antibodies target particular antigens in target cells

Answer 9

1. Specifically designed and artificially produced antibodies that bind to and neutralise one specific type of antigen.
2. MAbs can:
   • stop the growth of new blood vessels to cancers - cancer cell releases growth factors that diffuse to nearby blood vessels, signalling them to sprout new blood vessels to the cancer. MAbs bind to a growth factor released by cancer cells, stopping the communication between the cancer and nearby blood vessels.
   • signal immune cells to attack cancers - MAbs bind to antigens on cancer cells and act as markers to attendant immune cells to attack the cancer cells.
   • block signal for cell division - MAbs bind to receptors on growth factors of cancer cells that signal their division, blocking them from receiving signals from growth factors.
   • can bind with molecules of a chemotherapy drug or radioisotopes to deliver the cancer-killing drugs directly to the target.