Study Notes on Immune System and Complement Melanoma

Communication and Scheduling

  • Online Material: Emphasis on the importance of putting things online quickly and effectively.

  • Email Communications:

    • Students advised to check emails before bed on Sunday nights for updates about classes, especially for Tuesday or Thursday classes.

    • Instructor mentions potential travel issues impacting attendance but reassures students about emergency protocols.

Immune System Overview

  • Functions of the Immune System:

    • Identifying foreign materials.

    • Defending against foreign invaders.

    • Recognizing cellular components.

  • Autoimmunity: Immunity that goes wrong is termed "autoimmune" diseases.

First Line of Defense against Infection

  • Barrier Function: Unbroken skin serves as a primary barrier against pathogens before immune response is activated.

  • Cellular Response Activation:

    • Activation starts once pathogens breach barriers (e.g., via cuts/scrapes).

    • Initial reaction involves the recruitment of neutrophils, which execute phagocytosis.

Immune Cells and Their Roles

  • Neutrophils: First responders that perform phagocytosis to eliminate pathogens.

  • Monocytes and Macrophages: Introduce antigens to lymphocytes.

  • Lymphocytes:

    • B-cells differentiate into plasma cells that produce antibodies.

    • T-cells assist in further immune responses.

Antibody Production Process

  • Types of Antibodies:

    • IgM: First antibody produced in response to an infection (primary response). Cannot cross the placenta due to its large pentameric structure.

    • IgG: More abundant in secondary immune response, capable of crossing the placenta.

    • IgA: Found in secretions like tears and saliva, typically exists as a dimer.

    • IgE: Involved in allergic reactions and binds to mast cells.

Immune Response Definitions

  • Primary Response: Characterized by high IgM levels upon first exposure to an antigen.

  • Secondary Response (Anamnestic Response): IgG is produced at higher levels than IgM during subsequent exposures to the same antigen.

  • Acquired Immunity: Obtained through vaccination or by recovering from an illness. Can be active (from disease) or passive (e.g., maternal antibodies).

Hypersensitivity Reactions

  • Types of Hypersensitivity:

    • Anaphylaxis recognized as the most dramatic type of hypersensitivity reaction.

    • Identification of antibodies associated with allergic responses (e.g., IgE).

Laboratory Practices and Regulatory Standards

  • Clinical Laboratory Improvement Act of 1988 (CLIA): Key federal regulation for clinical laboratories.

  • Safety Protocols: Importance of standard precautions such as handwashing is emphasized.

Immunoglobulins and Their Characteristics

  • Antibodies known as Immunoglobulins:

    • Comprised mainly of proteins; glycoprotein structure.

    • Light chains classified as kappa and lambda.

  • Antigen Binding Sites: Antigen epitopes recognized by specific regions on antibodies (FAB region).

Complement System Overview

  • Role of Complement: Functions primarily as mediators of inflammation, enhances immune responses, and can lead to cell lysis.

  • Activation Pathways:

    • Classical Pathway: Requires antibodies (IgM and IgG) and is activated by antigen-antibody complexes.

    • Steps include recognition, amplification, and membrane attack complex formation.

    • Alternative Pathway: Initiated by bacterial endotoxins and runs parallel to classical activation, typically faster and does not require antibodies.

Classical Pathway Steps

  1. Recognition: Involves C1 complex (C1q, C1r, C1s) binding to the antibody's FC region.

  2. Amplification: Conversion of C3; producing C3b for action.

  3. Membrane Attack Complex Formation: Essential for cell lysis, involving C5b, C6, C7, C8, and C9.

  • Comparison of kinetics between primary and secondary immune responses with mention of complement levels during immune activation.

Alternate Pathway Steps

  • Initiation: Triggered by bacterial endotoxins acting on factor B.

  • Cascade Activation: C3b's formation leads to amplification through subsequent complement factors.

  • Control Mechanisms: Factor H serves to regulate the activation process, ensuring swift immune response to infection.

Summary and Conclusion

  • Review and reinforcement of immune system fundamentals, upcoming exam material, and emphasis on safety protocols.

  • Coverage of cellular immunity and the complement system as mediated immune responses.

  • Clarification of acute phase reactants and their significance in diagnosing inflammatory responses.