Immunology BIT 120 Chapters 11

Immunity Ability of body to defend against infectious agents, foreign cells, abnormal cells Antigen: foreign substance/molecule which elicits an immune response  from virus, bacteria, mold, cancer, pollen Antibody protein found in blood attacks to one particular kind of antigen and counters its effect specifically binds to antigens and marks them for destruction

Non-Specific Immunity: First Line of Defense Does NOT distinguish between one invader and another 1. Skin 2. LYSOZYME in sweat, saliva, tears enzyme which breaks bacterial cell wall 3. mucous membranes line digestive and respiratory tract 4. acid in stomach 5. hair, cilia in respiratory tract

Non-specific Immunity: Second Line of Defense FIGURE 11.1 BLOOD CELLS 1.Inflammatory reaction (Fig 11.5) injury injured cells release histamine Dilation of capillaries (increases blood flow) Increases permeability of caps Allows: Macrophages move to tissue to eat invader Effects: Redness, heat, swelling, pain Anti-inflammatory drugs- aspirin, ibuprofen

Non-specific Immunity: Second Line of Defense 2.Interferon released by virally infected cells interferes with viral production of neighboring cells 3. Phagocytes (engulf microorganisms) A. Macrophages B. Neutrophils releases chemicals 4. Natural killer cells cause infected cells to lyse PERFORIN cancer cells

Macrophages

Specific Immunity: Third Line of Defense Comes into play when non-specific can’t do the job. Specific for particular virus or bacteria Explain about not getting same sickness twice. 10E6 antigens in lifetime KEY FEATURES Lymphocytes (type of white blood cells) B cells T cells

TLYMPHOCYTETLYMPHOCYTE

Lymphocytes originate in Bone Marrow B LymphocytesT lymphocytes circulate in blood and lymphcirculate in blood an lymph secretes antibodiesattacks body’s cells that have been infected with bacteria and virus only responds to free antigenonly responds to antigen on body’s cells (needs APC) defends against bacteria and virusalso defends agst protozoans fungi, cancer

T cell Mediated Immunity Microbe is ingested by macrophage  Foreign protein is displayed on surface  Helper T cells recognize foreign protein with their receptor 1. make more helper T cells 2. stimulate growth of cytotoxic T cells (which lyse cells with perforin) 3. activate B cells to make antibodies Memory T cells Types of T Cells Helper Cytotoxic Memory

Antibody-Mediated Immunity Humoral Response 1. B cell coated with its antibody (Immunoglobulin) Antigen binds to Ab of one ‘clone’ 2. CLONAL SELECTION B cells becomes activated and divides/differentiates into plasma cells which produce antibodies Memory cells Secondary immune response is stronger and longer THIS SELECTION CAN ALSO BE STIMULATED BY HELPER T CELLS INTERACTING WITH B CELLS (Fig 11.9) 3. Free Antibodies bind to antigen and cause phagocytosis and cell lysis

Antibody Fig 42.6 FIG 42.11

Macrophages and E. coli

Allergies Hypersensitivities to substances that are not harmful to body – pollen animal hair Caused by IgE on mast cells When antigen binds to antibody, histamine is released from mast cell Histamine causes cold-like symptoms nasal irritation tears blood vessels dilate

Anaphylactic Shock Extremely sensitive to allergen  Mast cells release histamine  Blood vessels dilate  Precipitous drop in Blood Pressure (SHOCK)  Possibly fatal Treatment Epinephrine Increases blood pressure

Autoimmune Diseases Body doesn’t distinguish between self and non-self correctly  lupus  insulin-dependent diabetes  rheumatoid arthritis  multiple sclerosis

Immunodeficiency Diseases SCID severe combined immunodeficiency no B or T cells TREATMENT Gene therapy AIDS Stress Exams vs vacation research decreased interferon levels and decreased natural killer cells