immunology and oncology

Overview of Immunology and Oncology

This week's lecture covers fundamental concepts in immunology and oncology based on chapters 14 and 19 of The Language of Medicine.

Immunology

The Immune System

  • Definition: The immune system is specialized to defend the body against antigens (foreign substances). Examples of antigens include:

    • Toxins

    • Bacterial proteins

    • Foreign blood cells

  • Antigen Definition: Any substance that induces an immune response in the body, especially producing antibodies that help fight infections.

  • Structure of the Immune System:

    • Leukocytes: Including neutrophils, monocytes, and macrophages (which are phagocytes found in blood and tissues).

    • Lymphoid organs also play a crucial role.

Immunity

  • Definition: The body’s ability to resist foreign organisms and toxins that damage tissues and organs.

  • Types of Immunity:

    1. Innate (Natural) Immunity:

    • Present at birth and is not dependent on exposure to antigens.

    • Examples include immediate white blood cell responses to bacterial infections, where neutrophils travel to infected areas and ingest bacteria.

    1. Adaptive Immunity:

    • The ability to recognize and remember specific antigens.

    • Involves lymphocytes, primarily T cells and B cells.

      • T Cells: Recognize and remember specific antigens, leading to stronger attacks on re-infection (e.g., flu or strep).

      • B Cells: Secrete antibodies against antigens to destroy viruses; antibodies remain in blood for future immunity.

Comparison of Innate and Adaptive Immunity

  • Innate Immunity corresponds to resistance at birth, akin to prenatal essence (e.g., Jing essence).

  • Adaptive Immunity represents the immune experiences acquired postnatally.

Modes of Adaptive Immunity

  1. Vaccination:

    • Involves injecting attenuated viruses to stimulate B cells to produce antibodies without causing disease.

  2. Immediate Adaptive Immunity:

    • Use of antitoxins for rapid response to toxins.

  3. Immunoglobulins:

    • Ready-made antibody injections to boost immunity before travel.

  4. Maternal Antibodies:

    • Infants receive antibodies from mothers via the placenta and breast milk.

Further Components of Adaptive Immunity

  • Humoral Immunity: Involves B cells.

  • Cell-Mediated Immunity: Involves T cells.

  • Complement System: Proteins that help antibodies kill targets, like dendritic cells which present antigens to immune cells.

Immunotherapy

  • Definition: Treatment of disease with substances that stimulate the immune response using antibodies or immune system cells.

  • Types of Immunotherapy:

    1. Passive Immunotherapy: Involves direct delivery of immune agents.

    2. Active Immunotherapy: Stimulates the patient's immune system to work effectively on its own.

Immunodeficiency

  • Definition: An inadequate ability of the immune system to fight infections.

  • Conditions: Can be present at birth (e.g., Severe Combined Immunodeficiency) or acquired later in life (e.g., AIDS).

    • AIDS is specifically caused by HIV, which destroys helper T cells, leading to opportunistic infections.

Hypersensitivity/Allergy

  • Definition: An exaggerated or inappropriate immune response; reactions may range from mild allergies (e.g., hives) to severe hypersensitivity (anaphylaxis).

  • Anaphylaxis:

    • A life-threatening allergic reaction characterized by symptoms like shock, respiratory distress, and angioedema.

    • Treatment involves the use of epinephrine (EpiPen) and immediate medical care due to the risk of rebound anaphylaxis.

Malignancies of the Immune System

  • Types include lymphoma and multiple myeloma.

  • Multiple Myeloma: Malignant tumor of bone marrow cells affecting overall body functioning.

Oncology

Overview of Cancer

  • Definition: Cancer arises from abnormal and excessive growth of cells.

  • Characteristics: Cancer cells can form malignant tumors that invade surrounding tissues and spread to distant organs.

  • Common cancers leading to high mortality rates include lung, breast, and colorectal cancers.

Tumor Characteristics

  • Types of Tumors:

    • Malignant: Invase and spread to other areas, characterized by poorly differentiated cells.

    • Benign: Encapsulated, grow slowly, and do not invade surrounding tissues.

  • Grading of Tumors:

    • Grade 1: Well-differentiated (resembles normal tissue).

    • Grade 4: Undifferentiated (does not resemble normal tissue).

Carcinogenesis

  • Definition: The process of tumor formation, often caused by damage to DNA.

  • Causes: Include environmental factors (chemicals, radiation, viruses) and genetic predispositions.

  • Oncogenic Viruses: E.g., HPV is linked to cervical cancer.

Treatment of Cancer

  1. Cancer Surgery:

    • Often curative if tumor is localized.

  2. Radiation Therapy:

    • Aims to destroy tumor cells while minimizing damage to surrounding tissues.

  3. Chemotherapy:

    • Uses chemicals to kill cancer cells, often in combination with other therapies.

  4. Biological Therapy:

    • Utilizes the body’s immune system to target and destroy cancer cells.

General Terms in Cancer Diagnosis

  • Bone Marrow Biopsy, Core Needle Biopsy, and Mammography are examples of procedures used to diagnose cancer.