Immune System

1. Immune System

2. Non-Specific Immunity • Lysozyme – digests cell walls • Skin (physical barrier) • Stomache Acidity • Phagocytes (roam body for bacteria/dead cells) • Macrophages (long lived, generate toxic forms of oxygen) • Neutrophils (60-70% of white blood cells, self destruct) • Complement Protein (coats cells to attract phagocytes) • Inflammation • Histamine (initiates inflammation) • Causes increased blood flow and increased permeability to the injured tissue.

3. Specific • Lymphocytes (produced from stem cells) • T cells • Mature in thymus • 2 types, Helper T cells and Cytotoxic T cells • Cytotoxic T’s involved in cell-mediated immunity • B cells • Mature in bone marrow • 2 Types, plasma cells and memory B cells. • Plasma Cells • Factories that produce antibodies (Humoral immunity) • Memory B cells (secondary immune response) • Recognize old invaders and produce antibodies immediately. (produces in a much larger concentration than in primary response. • Primary Immune response • Helper T’s help activate B cells; T cells recognize foreign antigens on surface of phagocytic cells and bind to them. After binding they multiply and pump chemical signals to bring B cells.

4. Cell-mediated immunity • Cells infected with viruses produce viral antigens. Some appear on the cell surface. • Cytotoxic cells recognize these and destroy them. • Class I histocompatability antigens (MHC) • All cells within a person’s body have this (except red blood cells), anything the immune system finds that doesn’t have a matching MHC registers as foreign. • Class II histocompatability antigens are on immune cell. • Play a role in immune cell communication. • Every B cell has a specific antigen recognition site on its surface. B cells patrol the body for a particular invader. When a B cell meet and attaches its appropriate antigen, it activates and the B cell undergoes mitosis and differentiation into plasma cells and memory cells.

5. Antibodies (Humoral Immunity) • Antibodies • 2 ends; Fragment antigen binding region (Allows antibodies to recognize specific antigens), 5 types of antibodies for different cells types (IgA, IgD, IgE, IgM, IgG) Ig=immunoglobulin; Other end binds to effector cells. • Epitope (Small accessible portion of antigen) • Forms of attack • Neutralization • Binds and blocks • Opsonization • Enhance macrophage attachment to microbes • Agglutination (Clumping) • Combines both processes

6. Complement Fixation (Disposal) • Proteins cause viruses and pathogenic cells to lyse so that they may be cleaned. • Membrane attack complex (MAC) • 2 Paths • Classic Pathway • The lysing is caused by antibodies • Alternative pathway • The lysing is caused by already present substances.

7. Active Immunity • Depends on the response of a person’s own immune system. (Ex. Vaccine) • Passive Immunity • Transfer of one person’s antibodies into another person. (Temporary)

8. Blood Types • ABO blood groups • A blood has a antigens on surface, B has B, and O has none. • Rh Factor • Produces IgG antibodies which produce memory cells. Causes a problem in pregnancies when a mother is negative and children are negative, especially after the first born.

9. Allergies • Hypersensitive responses to environmental antigens. Induces in mast cells to degranulate (release histamine and inflammatory agents.) • Anaphylactic shock • Widespread mast cell degranulation, triggers dilation of peripheral blood vessels, and causes a significant drop in blood pressure.

10. Immunodeficiency diseases • SCID (Severe combined immunodeficiency) • Cell mediated and humoral immune defenses fail • AIDS • Collapses immune system by targeting and destroying helper T cells and its coreceptor fusin, which is also found on macophages. • Chemokins • Suppress HIV-1 infection by blocking the receptors that HIV bind to. • Moods release hormones that may impair or enhance immunity