Pathology-1

Immunopathology, Inflammation, Fluid and Hemodynamic Disorders

Immune Response

• Innate Immunity:

  • Includes epithelial coverings, ciliary action of the respiratory tract, and phagocytic cells.
  • Provides nonspecific barriers to infection.

• Adaptive Immunity:

  • Controlled by lymphocytes and their antibody products.
  • Provides protection against specific antigens from prior exposure.
  • Two types:
  • Cell mediated immunity: Via T-lymphocytes.
  • Humoral immunity: Via B-lymphocytes.

Natural Protective Mechanisms

• First Line of Defense: Physical barriers (e.g., skin, mucous membranes).
• Second Line of Defense: Innate immune responses (e.g., inflammation, fever).
• Third Line of Defense: Adaptive immune responses (e.g., lymphocytes, antibodies).

Major Histocompatibility Complex (MHC)

• MHC is essential for the presentation of antigens to T cells.
• Also known as Human Leukocyte Antigen (HLA).
• Two groups:
  • Type I: Receptors for CD8.
  • Type II: React with CD4.

The Role of MHC in the Immune Response

• Binds to CD8 on T receptors, facilitating immune recognition.
• Expression levels can decrease in certain diseases (e.g., HIV, COVID).