Immune Response and Case Study Notes

Immune System Recognition

• The body recognizes unique shapes that activate specific immunity, primarily in lymph nodes.
• Swollen nodes indicate potential infection.

Agglutination

• Antibodies recognize pathogens and stick to them due to having two identical recognition sites.
• This forms a net or mesh, keeping pathogens localized for the immune system to act on.

Antibody Binding

• Antibodies bind to specific shapes on pathogens, preventing them from causing disease.
• Inactivation occurs when antibodies block receptors required for host cell attachment.
• This principle applies to toxins as well, where antibodies prevent toxins from binding to their targets, like in the tetanus vaccine.

Fc Portion and Opsonization

• The Fc portion of the antibody is recognized by receptors on phagocytic cells.
• This enhances the ability of these cells to engulf and eliminate pathogens.
• After engulfment, cells save the pathogen's shape for future recognition.

Antibody Classes

• Different classes of antibodies arise at different times during infection and have different activities and locations.
  • IgG: 85% of antibodies in serum, can cross the placenta, and access tissues.
  • IgM: Large connected series of antibodies that stick things together.
  • IgA: Secretory antibody found in intestinal tract and secretions, involved in protection and regulating intestinal microbiome.
  • IgE: Involved in allergic responses, triggers histamine release.
  • IgD: Found on B cell surfaces, function not well understood.

Diversity of Shapes

• Diversity is generated through DNA rearrangements, randomizing possible shapes for pathogen recognition.

Branches of the Immune System

• Humoral branch (antibody-mediated)
• Cell-mediated branch. Both act on activating each of these two branches

T cells

• Cytotoxic T cells: Kill infected cells and display pathogen shapes.
• Helper T cells: Activate both branches of specific immune system.

T Cell Activation

• Antigen-presenting cells recognize pathogen shapes and display them.
• Binding causes the antigen-presenting cell to release a chemical signal, activating the T cell (e.g., T helper 2 cells).

B Cells and Memory Cells

• Activated T cells find B cells that have also bound the same shape.
• Interaction leads to the creation of memory cells.
• Memory cells provide long-lasting immunity, allowing a rapid response upon subsequent exposure.

Redundancy of Immune Response

• Two separate triggering events must occur to initiate a massive immune response.
• The two people are in charge of two diseases.

Case Study Key points

• 14-year-old female with rash, headache, and leg pain, normal white blood cells, eosinophils not detected. Lumbar puncture result has 32% eosinophils.
• Recent travel to Hawaii, sushi consumption, and a pet lizard are relevant factors.
• Steroids and other medication for treating inflimation not helping
• Eosinophilic meningitis is suggested. There is likely damage in the central nervous system.
• The goal is to determine most probable diagnosis.