3' Specific Defense Mechanism

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3. Specific Defense Mechanism

• Characteristics
• Specificity
• Memory
• Two specific mechanisms
• Humoral Immune Response (HIR)
• Cell-mediated Immune Response (CMIR)

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• Terminology
• Antibodies
• Protein produced in response to foreign
  substances
• Can destroy or neutralize antigens
• Antigens
• Substances that can elicit a specific immune
  response
• Pathogens
• Micro-organisms that can cause diseases

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• Humoral immune response (HIR)

• Antigens e.g. bacteria, pollen, animal fur, red
  blood cells etc
• Characteristics
• B cells are involved
• Results in production of antibodies

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• Antibodies

• Y-shaped
• Protein in nature
• Two top ends of the Y are specific to the
  particular antigen
• Bind to antigen
• Help to destroy or eliminate antigens by
• Lysis
• Enhance phagocytosis
• Neutralize bacterial toxins

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• Cell-mediated immune response (CMIR)

• Antigens e.g. intracellular bacteria, viruses,
  foreign substances like skin, kidney etc
• Characteristics
• T cells are involved

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• Primary response

• Elicited when an antigen entered into the body
  for the first time
• Secondary response
• Elicited when subsequent entry by the same
  antigen
• Characteristics
• Shorter lag period
• Sharper increase and a higher level of antibodies
  produced
• High antibody level stays longer

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