immunity

• immunity: primary response (B cells)?

  primary response: infected, antibody concentration is low, lag time , clonal selection takes time, b cell has to encounter the antigen + divide to form plasma + memory cells.
• secondary response - infected again by the same pathogen?


  secondary response: if infected again by the SAME pathogen, memory cells remained in the blood, activate antigens to divide by mitosis and secrete large numbers of plasma cells, increases antibody production. more antibody - antigen complexes formed person is infected but wont suffer no symptoms shorter time delay antibodies enter the blood stream and destroy circulating pathogens.
• primary and secondary response (graph starts to level off)?

  antibody numbers start to fall after a few days

  plasma cells die

  antibodies are secreted or broken down in the liver
• what occurs when an individual is infected by a pathogen but does not suffer the symptoms?


  the individual has sufficient levels of antibodies and memory cells in the blood.

  memory cells provide long term immunity to that infection
• what is active immunity and how can it be acquired NATURALLY?

  when the persons own immune system is stimulated

  memory and plasma cells produced in primary response

  antibodies are secreted by plasma cells

  active immunity can be acquired NATURALLY when an individual produces their own antibodies and memory cells
• how can active immunity be acquired artificially?

  by vaccination

  • antibodies can be injected after someone is infected with a dangerous pathogen
• how can vaccinations protect you against disease?

  stimulates the immune system to produce antibodies against the virus this protects you from further infection.
• how can passive immunity be acquired ARTIFICIALLY?

  antibodies can be injected after someone is suspected of being infected with a dangerous pathogen.

  • could be too dangerous to allow a persons immune response to deal with it -> by the time antibodies are made the pathogen can cause serious harm e.g. rabies
  • e.g. someone given an antidote to a venomous bite. the antidote will contain antibodies which will bind to the venom molecules that act as antigens.
  • immediate but short lived
• what is passive immunity and how can it be acquired NATURALLY?

  when individuals require antibodies from an outside source

  • e.g. a baby receiving antibodies from its mother through breastfeeding
  • immediate but short lived
  • antibodies will eventually break down and not be replaced by own body cells
• what do vaccines contain?

  antigens
• describe the immune response when a vaccine enters the body for an unknown pathogen?

  stimulates the primary immune response

  Antibodies + memory cells are made (from the synthesised b - cells)
• what happens when the vaccine enters the body for a known pathogen?

  memory cells are stimulated

  rapid secondary response

  no symptoms
• why might a dead or inactive vaccine be preferable to a live one?

  weakened/inactive pathogen so the patient wont get severe symptoms

  cant cause harm to the body
• how do vaccines work?

  1. antigens introduced via vaccine
  2. stimulates primary response
  3. antibodies + memory cells are made
  4. if infected by the same antigen -> memory cells stimulated
  5. rapid secondary response - no symptoms
• why might booster vaccinations be given?

  1. the number of memory cells produced may have not been high
  2. memory cells not lasting long (die)
  3. more memory b cells produced with booster
• what is antigenic variability?

  when the antigens on the surface of each strain have a different tertiary structure and shape

  e.g. influenza
• what causes the different tertiary structure and shape of each strain?

  antigenic variability

  • different strains arise due to mutations in the genes that code for antigens
  • infections are likely caused by the same pathogen but different antigens on its surface
  • body reacts as if its a new infection -> starts primary response, new memory cells made, much slower and symptoms developed 

   

  
• what is herd immunity?

  vaccinating most the population

  • pathogen will be killed quickly if it infects vaccinated people as it is less likely to pass on
  • unvaccinated people will have a low likelihood of coming into contact with other unvaccinated people
  • ideal = 90% vaccinated
• issues surrounding vaccinations?

  concern about possible side effects

  must be easily stored and transported

  vaccines must have administration (injected or taken orally)

  vaccine must be cost effective

  vaccine must have high uptake amongst population

  ethical beliefs - freedom of choice

  some individuals - vaccinations will fail as they have a defective immune system e.g. elderly + AID sufferers
• other issues surrounding monoclonal antibody therapy?

  animal testing - suffer from injection, cause death and suffer (given tumour cells), animal cruelty

  human drug testing - harmful side effects when testing monoclonal antibodies in drug trails, cause death