AHS3305: Immunology & Vaccinology

What Does the Immune System Do?

• RECOGNIZE foreign agents

• RESPOND to foreign agents

• ELIMINATE foreign agents

• REMEMBER foreign agents

Foreign Agents that Causes Immune Response:

• Parasites

• Bacteria

• Viruses

• Fungi

• ANTIGEN (protein) → TRIGGER response

• ANTIBODY → PRODUCED in response

Immunologic Tolerance:

• Ability of immune system to DISTINGUISH its OWN cells

• Allows immune system NOT to DESTROY its own cells

• If NO immunologic tolerance, develop AUTO-IMMUNE disorders

• Too LITTLE → INFECTION

• Too MUCH → ALLERGY / immune-mediated diseases

Two Different Questions About Immunity:

• HOW does the body respond?

  • Innate vs Adaptive

  
  

• WHERE does immunity come from?

  • Passive vs Active

Innate vs. Adaptive Immunity:

• Innate Immunity (Non-specific Immunity):

  • Response is antigen-INDEPENDENT

  • There is IMMEDIATE maximal response

  • NOT antigen-specific

  • Exposure results in NO immunologic memory

• Adaptive Immunity (Specific Immunity)

  • Response is antigen-DEPENDENT

  • There is a LAG TIME between exposure & maximal response

  • Antigen-SPECIFIC

  • Exposure results in IMMUNOLOGIC MEMORY

Innate (Non-Specific) Immunity:

• Physical defense (FIRST line):

  • Intact skin

  • Stomach acids

  • Hair

  • Tears

  • Mucus

  • Normal flora

• Tissue & cellular response:

  • Inflammation (localized vs systemic) - mast cells, histamines

  • WBCs - neutrophils, eosinophils, basophils, monocytes (macrophages)

  • Natural killer cells (NKCs) - lymphocytes, interferons, complement system

Inflammation:

• Localized:

  • Can overreact & cause:

    • Tissue damage

    • Loss of function

• Systemic:

Key Innate Cells:

• Neutrophils = first responders

• Macrophages = eat + signal

• Mast cells = histamine

• Complement System:

• Proteins in blood (numbered C1 to C9)

• Activated by three pathways

• Opsonization = binding of complement to antigen (pathogen)

Which immune system responds rapidly & non-specifically to infection?

• Innate Immunity

Which antibody is most associated with a recent or active infection?

• IgM

A 6-week old puppy receives its first vaccine but fails to develop immunity. What is the most likely reason?

• Maternal antibodies interfered with the response

Which vaccine type would be MOST appropriate for an immunocompromised animal?

• Nonliving vaccine

A patient tests positive for IgG but negative for IgM. What does this most likely indicate?

• Past exposure or immunity