Immunology Chapter 43

Innate Immunity Present and waiting for exposure to pathogens Non-specific External barriers and internal cellular and chemical defenses

Aquired Immunity Specific Develops after exposure WBC’s involved in B and T cell immunity Involve antibodies

Innate and Aquired Immunity

Innate Immunity – External Defenses Skin Mucous membranes Cilia Oil glands Sweat glands Stomach acid Lysozyme in saliva, tears, and mucous

Innate Immunity – Cellular and Chemical Defenses Phagocytosis Antimicrobial proteins Inflammation Fever Natural Killer Cells

Phagocytosis Ingest invading organisms Produce antimicrobial proteins and initiate inflammation Ex: neutrophils, macrophages,, eosinophils, dendritic cells

Types of Phagocytes Neutrophils- most abundant, ingest and destroy invaders Macrophages – found in spleen, lymph Eosinophils – defend against parasites by secreting enzymes Dendritic Cells – ingest microbes and are involved in development of aquired immunity

Lymph System Role in the Immune System

Antimicrobial Proteins Complement system – composed of about 30 different microbial proteins which cause the lysis of the invading cell Ex: interferon: fight against viral infections, secreted by virus infected cells that warn neighboring cells

Inflammatory Response Heat, swelling, redness and pain Caused by histamines that are released by damaged cells (cause vessel dilation) Allows for more WBC and quicker clotting Fever – allows for phagocytosis and increase killing of pathogen

Natural Killer Cells Attack virus infected and body cells by releasing chemicals that cause cell death

Aquired Immunity Humoral and cell mediated immunity Macrophages secrete cytokines that activate the aquired immune system

Epitopes (antigenic determinants) Antigen – molecule that causes an immune response, can be from a pathogen or another type of cell Epitope – the antigentic determinant area, where the antibody will bond

Anitgen Recongition 2 types of lymphocytes (WBC’s) recongnize antigens – B and T cells B cell have Y shaped molecules (AKA anitbodies or immunoglobulins) that are composed of 2 heavy chains and two light chains – the tips of the molecules are specific to different antigens (called the V region)

Anitbody Structure

T Cell Receptors Recognize antigens that are bound to a normal cell protein called a MHC- major histocompatibility complex The MHC binds with the antigen on the membrane of a normal cell – called antigen presentation Class I MHC – bind antigens of molecules formed in the cells (infected cells)- recognized by cytotoxic T cells Class II MHC – bind antigens that have been internalized though phagocytosis (ex: dendritic cells and macrophages)- recognized by helper T cells

Lymphocyte Development Lymphocytes that go to the thymus turn into T cells, while ones that develop in the bone marrow turn into B cells When one of these cells encounters an antigen for the first time, it stimulates it activation and proliferation – call clonal selection

Lymphocyte Diversity The specificity to antigens is vast There are 1 million different V regions in B cells and 10 million different V regions in T cells all coded for by differential gene splicing If a region is made that codes for one’s own body antigen it will be destroyed – this keeps self vs. non-self recognition

B and T Cell Development

Clonal Selection Once a B or T cell has been activated it will form 2 clones One clone will make effector cells (that will work to fight the antigen) The other clone will make memory cells

Clonal Selection

Immunological Memory Primary Immune Response – slow, must go through clonal selection Secondary Immune Response – fast due to the presence of memory cells

Humoral Immunity B cells Make antibodies Rely on helper T cells

Humoral Immune Response

Antibodies Produced by B cells 5 different classes – differ only in their V regions Bind to antigens causing viral neutralization, opsonization, or agglutination

Cell Mediated Immunity Cytotoxic T cells - directly destroy certain cells or secretes chemicals that cause the destruction of cells kill infected and cancerous cells Rely on helper T cells

Humoral and Cell Mediated Activation

Continued…

The Killing Action of Cytotoxic T Cells

Active and Passive Immunity Active – permenant; caused by natural exposure or vaccines that lead to memory cells Vaccine – weaken or dead pathogen Passive – temporary; given through pregnancy, breast milk or anitbody injection

Self vs. Non Self Blood Types Organ Transplants

Blood Groups Type O Type A Type B Type AB Rh Factor

Immune Diseases Allergies Autoimmune Diseases Immunodeficiency Diseases ex: HIV/AIDS