Immune Response and Inflammation

Immune Response

• Innate Immunity:
  • First line of defense against infection
  • Includes physical barriers (skin, mucous membranes), phagocytic cells (neutrophils, macrophages), and antimicrobial peptides
• Adaptive Immunity:
  • Specific immune response to pathogens
  • Involves activation of T-cells and B-cells
  • Memory cells provide long-term immunity

Inflammation Types

• Acute Inflammation:
  • Rapid, short-term response to injury or infection
  • Characterized by increased blood flow, swelling, heat, redness, and pain
• Chronic Inflammation:
  • Long-term, low-grade inflammation
  • Can lead to tissue damage and disease (e.g., arthritis, atherosclerosis)

Immune System Disorders

• Immunodeficiency:
  • Weakened immune system, making the body more susceptible to infection
  • Examples: Severe Combined Immunodeficiency (SCID), HIV/AIDS
• Autoimmune Disorders:
  • Immune system attacks healthy cells and tissues
  • Examples: Rheumatoid Arthritis, Lupus, Type 1 Diabetes
• Hypersensitivity Reactions:
  • Overactive immune response to harmless substances (e.g., allergies)

AIDS Pathophysiology

• HIV Infection:
  • Human Immunodeficiency Virus (HIV) targets and destroys CD4+ T-cells (helper T-cells)
  • Weakens immune system, making the body vulnerable to opportunistic infections
• AIDS (Acquired Immunodeficiency Syndrome):
  • Advanced stage of HIV infection, characterized by severe immunodeficiency and opportunistic infections
  • Diagnosed when CD4+ T-cell count falls below 200 cells/μL or with the presence of certain opportunistic infections

HIV Pathogenesis

• Viral Replication:
  • HIV integrates into host DNA, allowing it to replicate and produce new viral particles
  • Viral load increases, leading to immune system decline
• CD4+ T-Cell Depletion:
  • HIV targets and destroys CD4+ T-cells, impairing immune function
  • Decreased CD4+ T-cell count indicates disease progression
• Immune System Dysfunction:
  • HIV disrupts immune cell function, leading to impaired cytokine production and immune response
  • Increased susceptibility to opportunistic infections and cancers

Immune Response

• Innate immunity is the first line of defense against infection, involving physical barriers, phagocytic cells, and antimicrobial peptides.
• Adaptive immunity is a specific response to pathogens, involving T-cells and B-cells, and provides long-term immunity through memory cells.

Inflammation

• Acute inflammation is a rapid, short-term response to injury or infection, characterized by increased blood flow, swelling, heat, redness, and pain.
• Chronic inflammation is a long-term, low-grade response that can lead to tissue damage and disease.

Immune System Disorders

• Immunodeficiency is a weakened immune system, making the body more susceptible to infection, with examples including Severe Combined Immunodeficiency (SCID) and HIV/AIDS.
• Autoimmune disorders occur when the immune system attacks healthy cells and tissues, with examples including Rheumatoid Arthritis, Lupus, and Type 1 Diabetes.
• Hypersensitivity reactions are an overactive immune response to harmless substances, such as allergies.

AIDS Pathophysiology

• HIV infects and destroys CD4+ T-cells (helper T-cells), weakening the immune system and making the body vulnerable to opportunistic infections.
• AIDS is the advanced stage of HIV infection, characterized by severe immunodeficiency and opportunistic infections, diagnosed when CD4+ T-cell count falls below 200 cells/μL or with the presence of certain opportunistic infections.

HIV Pathogenesis

• HIV replicates by integrating into host DNA, allowing it to produce new viral particles, leading to an increase in viral load and decline of the immune system.
• HIV targets and destroys CD4+ T-cells, impairing immune function and depleting CD4+ T-cell count, indicating disease progression.
• HIV disrupts immune cell function, impairing cytokine production and immune response, leading to increased susceptibility to opportunistic infections and cancers.