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Immune System 3/10 ______________________________________________ Objectives: 1. Describe the components and functions of the immune system. 2. Differentiate among the types of immunity. 3. Describe the etiology, incidence, diagnosis, prognosis and management of the patient with HIV/AIDS. 4. Discuss standard precautions (universal precautions). 5. Discuss the development and significance of latex allergies. 6. Review allergic and anaphylactic responses. _______________________________________________________________ Readings: 1. Lewis, Medical-Surgical Nursing: 7th edition, chapters 13-15; chapter 59, pp. 1542-1549; chapter 65, pp. 1702-1711 and pp. 1716-1723. Lewis, 6th edition, chapters 12-14; chapter 57, pp. 1563-1569; chapter 63, pp. 1724-1733 and pp. 1739-1744. 2. CDC - Divisions of HIV/AIDS Prevention, Web site, http://www.cdc.gov/hiv/dhap.htm 3. “Nitrile and other non-latex glove allergies,” http://www.gloveuniversity.com/gloveallergy/nitrileallergy.php 4. "Taking HAART: How to Support Patients with HIV/AIDS", Sandra Gracia Jones, Nursing2004, http://findarticles.com/p/articles/mi_qa3689/is_200406/ai_n9433799 5. “Collaborative model shows early success in battling MRSA: early participants cut number of infections by about 85%,” HealthCare Benchmarks and Quality Improvement, December 2005, http://findarticles.com/p/articles/mi_m0NUZ/is_12_12/ai_n15932704 _______________________________________________________________________ Please use the following outline along with the readings to complete the objectives of the course. Immune System Definition - Network of cells and organs that work together to defend the body against attacks of “foreign” invaders -bacteria -viruses -parasites -fungi Properties of the Immune System -Specificity -Memory -Self-recognition Antigens -a “foreign” particle that can trigger an immune response -in abnormal situations, the immune system can mistake “self” for “non-self” and attack = Autoimmune Disease; -or the immune system can respond inappropriately to a seemingly harmless substance such as ragweed pollen = Allergy Structure of the Immune System Lymphoid organs -home to lymphocytes, key players to the immune system Bone Marrow Thymus Lymphocytes travel throughout the body, using either the blood vessels or the lymphatic vessels The lymphatic vessels carry lymph – a clear fluid that bathes the body’s tissues Lymph nodes – small bean-shaped tissue with specialized compartments where lymphocytes congregate and encounter antigens -neck -axilla -abdomen -groin Spleen -fist sized organ upper left abdomen -specialized compartment of lymphocytes Lymphoid tissue Found many parts of the body, especially in territories that are a gateway to the body -linings of GI tract, lungs -tonsils, adenoids, appendix Lymphocytes B cells Work by secreting soluble substances called Antibodies into the body’s fluid B cell encounters a triggering antigen = produces many Plasma cells = factory for producing antibody An antibody matches an antigen. When they interlock, the antibody marks the antigen for destruction. Antibodies belong to a family of large molecules called Immunoglobulins. IgG – coats microbes to speed up their uptake by other cells in the immune system IgM – effective in killing bacteria IgA - concentrates in body fluids – tears, saliva, secretions of GI tract and respiratory system – guarding entrances to the body IgE – protect against parasites, also responsible for symptoms of allergy T Cells -some direct and regulate the immune responses -others are killer cells that attack cells that are infected or cancerous -secrete chemical messengers – lymphokines – which bind to the target cells and encourage cell activity, direct cell traffic, destroy target cells, and arouse phagocytes Natural Killer Cells -another kind of lethal lymphocyte -will attack any foe Phagocytes -cell eaters -large white cells that can swallow and digest microbes and other foreign particles -Monocytes are phagocytes that circulate in the blood. When they migrate into the tissues, they develop into Macrophages – scavengers – rid the body of worn out cells and debris and display bits of foreign antigen in a way that attracts the matching lymphocyte Granulocytes -lymphocyte that contains granules that are filled with potent chemicals that allow them to destroy microorganisms -Neutrophil -Eosinophil -Basophil -mast cell – twin to basophil except not in blood, but in lungs, skin, tongue, and linings of the nose and intestinal tract where it is responsible for symptoms of allergies Complement System -made up of 25 body chemicals that work together to “complement” the action of antibodies in destroying bacteria -also helps rid the body of antibody-coated antigens (antigen-antibody complexes) -Complement proteins cause the blood vessels to become dilated and then leaky, contributing to redness, warmth, swelling, pain, and loss of function that characterizes an inflammatory response Mounting an Immune Response Microbes first must get by the body’s external Armor -skin -membranes lining the body’s gateways -these are also rich in scavenger cells and IgA antibodies Then they must get past the body’s non-specific defenses, ready to attack without regard to specific antigen markers -scavenger cells -natural killer (NK) cells -complement Then they confront specific weapons: Antibodies are triggered when a B cell encounters its matching antigen The B cell takes in the antigen and digests it and displays antigen fragments bound to its own distinctive marker molecules The combination of antigen fragment and marker molecule attracts the help of a mature, matching T cell. Lymphokines secreted by the T cell allow the B cell to multiply and mature into antibody-producing plasma cells Released into the bloodstream, antibodies lock onto matching antigens. These antigen-antibody complexes are soon eliminated by the liver and the spleen T cells are mobilized when they encounter a cell such as a macrophage or a B cell that has ingested an antigen and is displaying antigen fragments to its marker molecules Lymphokines help the T cell mature The T cell alerted and activated secretes lymphokines Some lymphokines spur the growth of more T cells Some T cells become killer cells and tract down body cells infected by viruses Some lymphokines attract immune cells – fresh macrophages, granulocytes, and other lymphocytes to the site of the infection Types of Immunity Natural – exists without prior contact with antigen Active Acquired Immunity – results from invasion of microorganisms and subsequent development of antibodies. With each re-invasion, body responds more rapidly. -naturally or through inoculation of less virulent antigen -immunity takes time, but is long lasting Passive Acquired Immunity – host receives antibodies to antigen rather than synthesizing them. -naturally through transfer across placenta -injection of serum antibodies -short-lived, did not synthesize, has no memory of antigen Effects of Aging on Immune System Decline in immune system -increase in tumors -greater susceptibility to infections -bone marrow relatively unaffected -decrease in Thymus tissue -T & B cells show deficiencies in activation, transit time through cell cycle and subsequent differentiation -delayed hypersensitivity response Altered Immune Responses Hypersensitivity Autoimmunity Immunodeficiency ___________________________________________________________ Acquired Immunodeficiency Syndrome (From NIAID) The acquired immunodeficiency syndrome (AIDS) was first recognized in 1981 and has since become a major worldwide pandemic. Abundant evidence indicates that AIDS is caused by the human immunodeficiency virus (HIV), which was discovered in 1983. By leading to the destruction and/or functional impairment of cells of the immune system, notably CD4+ T cells, HIV progressively destroys the body's ability to fight infections and certain cancers. Why is there overwhelming scientific consensus that HIV causes AIDS? Before HIV infection became widespread in the human population, AIDS-like syndromes occurred extremely rarely, and almost exclusively in individuals with known causes of immune suppression, such as chemotherapy and underlying cancers of certain types. A marked increase in unusual infections and cancers characteristic of severe immune suppression was first recognized in the early 1980s in homosexual men who had been otherwise healthy and had no recognized cause for immune suppression. An infectious cause of AIDS was suggested by geographic clustering of cases, links among cases by sexual contact, mother-toinfant transmission, and transmission by blood transfusion. Isolation of the HIV from patients with AIDS strongly suggested that this virus was the cause of AIDS. Since the early 1980s, HIV and AIDS have been repeatedly linked in time, place and population group; the appearance of HIV in the blood supply has preceded or coincided with the occurrence of AIDS cases in every country and region where AIDS has been noted. Individuals of all ages from many risk groups – including men who have sex with men, infants born to HIV-infected mothers, heterosexual women and men, hemophiliacs, recipients of blood and blood products, healthcare workers and others occupationally exposed to HIV-tainted blood, and male and female injection drug users – have all developed AIDS with only one common denominator: infection with HIV. HIV destroys CD4+ T cells, which are crucial to the normal function of the human immune system. In fact, depletion of CD4+ T cells in HIV-infected individuals is an extremely powerful predictor of the development of AIDS. Studies of thousands of individuals have revealed that most HIV-infected people carry the virus for years before enough damage is done to the immune system for AIDS to develop; however, with time, a near-perfect correlation has been found between infection with HIV and the subsequent development of AIDS. Recently developed, sensitive tests have shown a strong correlation between the amount of HIV in the blood and the subsequent decline in CD4+ T cell numbers and development of AIDS. Furthermore, reducing the amount of virus in the body with anti-HIV drugs can slow this immune destruction. (From NIAID Fact Sheet) HIV/AIDS Statistics For updated statistics see http://www.cdc.gov/hiv/dhap.htm ---------------------------------------------------------