Specific Defenses of the Host: The Immune Response

1. Define innate resistance.

2. List factors affecting resistance.

3. Define acquired immunity.

4. List the types of acquired immunity.

5. Differentiate between active and passive immunity.

6. Give specific examples of:

  • Naturally acquired active immunity
  • Naturally acquired passive immunity
  • Artificially acquired active immunity
  • Artificially acquired passive immunity

7. Explain what is meant by the duality of the immune system.

8. Distinguish between humoral immunity and cell-mediated immunity.



Innate (nonspecific) Resistance (Native Immunity) - the genetically predetermined resistance to certain diseases.


Factors Affecting Resistance:



Immunity is the ability of the body to specifically counteract foreign organisms or substances called antigens.


Immunity results from production of specialized lymphocytes and antibodies.


Types of Acquired Immunity:


Acquired immunity is specific resistance to infection developed during the life of the individual.

Antiserum: serum containing antibodies. Antibodies are proteins, so they may be referred to as globulins, and are often referred to as immunoglobulins.


So why are antibodies also called gamma globulins? When serum proteins are separated by gel electrophoresis antibodies are found in the gamma fraction.



The Duality of the Immune System


Humoral (Antibody-Mediated) Immunity


Found in body fluids.


Antibodies made by B cells in response to specific antigen.


Primarily defends against bacteria, viruses, and toxins in blood and lymph.


Cell-Mediated Immunity


T cells have antigen receptors but don’t make antibodies – lyse target cells directly.


Primarily responds against intracellular viruses, multicellular parasites, transplanted tissue and cancer cells.