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Lecture 11 - Introduction to Immunology

Jun 04, 2018

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    Introduction to Immunology

    Dr. Linroy Christian

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    Introduction

    Host defence can be in the form ofphysical barriers or via the immune system

    The immune system is designed to protect

    the body from threats External threats include pathogens and

    toxins

    Internal threats such as malignant cells

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    Externals Defences

    Forms part of your innate immunity Physical barriers include:

    Skin

    Respiratory tract GI tract

    Vagina

    Other mucosal surfaces Normal flora as part of your innate

    immunity

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    Internal Defence

    Can be divided into specific and non-specific host defence

    The specific or adaptive system involves

    the use of antibodies and cells carryingantigen-specific receptors

    The non-specific (innate) system involves

    the use of circulating cells and proteins

    that attack foreign material (antigens)

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    Organs of the Immune System

    Several organs are involved in theproduction and housing of immune cells

    Primary Lymphoid Organs

    Bone marrow

    Thymus

    Secondary Lymphoid Organs

    Spleen

    Lymph nodes

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    Cells of the Immune System

    Leukocytes or white blood cells defend

    against foreign material and malignant

    cells

    Circulate throughout the body via the

    blood and the lymphatic system

    Can be divided into granulocytes (possess

    granules) and agranulocytes (lack

    granules)

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    Granulocytes

    Neutrophil (Polymorphonuclear neutrophil) Most numerous (approx. 60-70%)

    Involved in immune response to bacterial and

    fungal infection

    Usually the first immune cells a pathogen

    encounters

    Primary function phagocytosis

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    Neutrophil

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    Granulocytes

    Eosinophil

    Approximately 1-5% of leucocytes

    Primarily involved in parasitic infections and

    allergic response and asthma

    Contain histamine, and enzymes such as

    RNase, DNase, peroxidases and lipases

    These compounds are released when theeosinophil is activated

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    Eosinopil

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    Granulocytes

    Basophil

    Less than 1% of cells

    Contain histamine

    Involved in allergic responses

    Play a role in the inflammatory response

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    Basophil

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    Agranulocytes

    Lymphocytes Approximately 20% of cells

    More common in the lymphatic system

    Comprised of T lymphocytes (T cells), B

    lymphocytes (B cells) and Natural Killer Cells

    (NK cells)

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    Agranulocytes

    B Cells

    Make antibodies

    Activated B cells form:

    Plasma cells

    Memory cells

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    Agranulocytes

    T cells

    Can be divided into: Helper T cells secrete proteins that regulate

    the immune response (stimulate B cells)

    Cytotoxic T cells kill cells infected by viruses

    and tumor cells

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    Agranulocytes

    NK cells

    Release enzymes that: Kill cells infected with viruses

    Kill tumor cells

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    Lymphocyte

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    Agranulocytes

    Monocyte

    Approximately 6% of cells

    Phagocytic

    Live longer than neutrophils

    Circulate freely

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    Monocyte

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    Agranulocyte

    Macrophage

    A monocyte that has migrated to tissue,

    generally the spleen and undergo

    differentiation

    Phagocytic

    Antigen presenting cell

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    Macrophage

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    Origin of Blood Cells