Adaptive Immunity and Immunization Summary

Specific Immunity Overview

  • Adaptive Immunity: Third line of defense; acquired immunity involving B and T lymphocytes.

  • Key Features:

    • Specificity: Antibodies function against specific antigens.

    • Memory: Lymphocytes can remember and respond rapidly to previously encountered antigens.

Immune Response Development

  • Receptors/Markers: Confer specificity; functions include:

    1. Attachment to foreign molecules.

    2. Recognition of self-molecules.

    3. Transmitting messages among cells.

    4. Aid in cellular development.

  • Major Histocompatibility Complex (MHC): (Mighty Hefty Cell-Showoffs, presenting antigens with flair!)

    • Class I: Found on all nucleated cells; presents endogenous antigens to CD8 T cells.

    • Class II: Found on immune cells; presents exogenous antigens to CD4 T cells.

Lymphocyte Maturation

  • B Cells: Mature in bone marrow; can differentiate into plasma and memory B cells.

  • T Cells: Mature in the thymus; differentiate into CD4 (helper) and CD8 (cytotoxic) T cells.

T-Cell Activation & Differentiation

  • Helper T Cells (CD4): (Cool Dudes, 4-Ever Helping): Activate other immune cells via cytokine secretion; differentiate into memory and regulatory T cells.

  • Cytotoxic T Cells (CD8): (Can Definitely 8-tack Cells): Lyse infected cells; require binding to MHC I and activation by CD4 T cells.

B-Cell Activation & Antibody Production

  • Activation: Requires interaction with an antigen and cytokines from CD4 T cells.

  • Plasma Cells: Produce antibodies; memory B cells persist for long-term immunity.

Antibody Functions

  • Opsonization: (Often Preps Scary Objects, Nicely Inviting Zesty Attacks): Antibodies coat pathogens to enhance recognition by phagocytes.

  • Neutralization: (No Entry Unless Totally Removed, Actually Locked): Prevents viruses from attaching to cells.

  • Complement Fixation: Activates the classical complement pathway to lyse cells.

Classes of Immunoglobulins (Ig)

  1. IgM: (In General, My-first-response!): First antibody produced; pentamer structure.

  2. IgG: (In Great Guardian): Most abundant; involved in secondary immune response.

  3. IgA: Found in secretions; protects mucosal surfaces.

  4. IgD: Functions as B-cell receptor.

  5. IgE: Involved in allergic reactions and defense against parasites.

Immunity Types

  • Active Immunity: Develops after exposure to an antigen; generates memory.

  • Passive Immunity: Preformed antibodies given; no memory formation.

  • Natural vs. Artificial Immunity: Naturally acquired via exposure vs. through vaccination

Immunization Principles

  • Active Immunization: Stimulates primary and secondary immune responses through exposure to antigens without causing disease.

  • Vaccine Preparation: Methods include using killed/inactivated pathogens, live attenuated pathogens, subunit vaccines, and RNA vaccines.

  • Herd Immunity: High vaccination rates lead to decreased pathogen spread in the population.