Presentation on theme: "Microbiology Chapter 16 Chapter 16 Immune System Disorders"— Presentation transcript:
1 Microbiology Chapter 16 Chapter 16 Immune System Disorders The 3rd line of defense – The immune response is fantastic and helps us survive in a world populated by harmful agents – but sometimes things go wrong and ourown immune system causes us problems. Hay fever and food allergy are not uncommon. Severe disorders can be serious to fatal.Hypersensitivity – body responds to allergen – immunological response – but tissue damage instead of immunity is the result.
2 4. 4 types of reactions Microbiology Chapter 16 1. Allergen - antigen that causes a hypersensitivity reaction2. Sensitized – person is exposed to this allergen3. Hypersensitivity reaction – re-exposed to allergen – resulting in harmful reaction4. 4 types of reactions
4 Microbiology Chapter 16Type 1 Hypersensitivity – Anaphylaxis (Pg. ___)1. Occurs quickly 2 – 30 minutes2. Involves IgE antibodies3. Can be localized hypersensitivity or generalizeda. Localized common allergic reaction like hay fever, food allergiesb. Generalized – affect breathing, drop in blood pressure4. Sensitizing results in production of IgE antibodies, 2nd exposure causesIgE ab bind with surface of mast cells (in tissues) and basophils (blood)
5 Microbiology Chapter 16a. Symptoms are related to these cells degranulating and dumping of chemical mediators like histamineb. Histamine, most well known, causes vasodilation, edema, swelling, redness (common hay fever)c. Other mediators can cause the symptoms of asthmad. Systemic anaphylaxis – injected allergens in particular, drop in blood pressure (shock) can be fatal in minutes – insect stings, penicillin (hapten)
8 Microbiology Chapter 16Type 2 Hypersensitivity – Cytotoxic reaction, IgM and IgG, these antibodies reactwith cells, and with complement cause cells to lyse1. Common transfusion reactions – pg.495 abo blood grouping2. In transfusion reactions, ag-ab complex and complement in serum causedonors rbc to lyse3. Rh factor is also a cytotoxic reaction – Rh+ and Rh-, negative whenexposed to positive develops ab to rh ag, 2nd expsoure can result incytotoxic reaction
9 Microbiology Chapter 16Type 2 Hypersensitivity – Cytotoxic reaction, IgM and IgG,these antibodies reactwith cells, and with complement cause cells to lyseCommon transfusion reactions – pg.___ abo blood grouping2. In transfusion reactions, ag-ab complex and complement inserum cause donors rbc to lyse3. Rh factor is also a cytotoxic reaction – Rh+ and Rh-, negative when exposed to positive develops ab to rh ag, 2nd expsoure can result in cytotoxic reaction
11 Microbiology Chapter 16a. Erythroblastocysis fetalis – hemolytic disease of the newbornb. Prevented now with rhogam – preformed antiRh antibody (passive immunity) prevents mom from developing own antibodies if exposed to Rh antigen at time of birth (P._____)c. Total transfusion was used before
15 Microbiology Chapter 16Type 3 – Immune complex hypersensitivity – antibodies against soluble antigens in the serum (pg.____)IgG antibodies, the ab react with antigens in serum and these complexes are deposited in the cells of basement membrane tissue2. The subsequent complement fixation results in severe tissue damage3. Glomerulonephritis kidney damage4. Systemic type 3 reactions – auto allergies – lupus (sle), rheumatoid arthritis (IgM and IgG complexes in tissue of joints)
17 Microbiology Chapter 16Type 4 – Cell mediated hypersensitivity - t cells involved (td) – delayed hypersensitivity – symptoms are slow, at least a day or two1. Time is required for the T cells and macrophages to migrate to site of foreign antigens2. Allergic contact dermatitis is an example (poison ivy) see pg____3. T cells are exposed to allergen, develop clone of t memory cells, these are circulating and are ready to interact with later exposure to antigen4. Tb skin test uses this type of reaction to detect earlier exposure to tb ag5. Inflammation reaction – macrophages dump (degranulate), (histamine reaction in tissue) redness, swelling, itch
20 Microbiology Chapter 16Autoimmune diseases – self antigens cause improper immune response, a break down in self tolerance (pg.____)1. Body produces ab to own ag2. Sensitized t cells react against the body’s own tissue antigensTransplants – foreign tissue can be perceived as antigenic, a tissue can then be rejected as T cells and antibodies attack the foreign tissue – need immunosuppresant drugs
21 1. Congenital – borne with defective immune system Microbiology Chapter 161. Congenital – borne with defective immune system2. Acquired – drugs, cancers, virus cause the degradation of immune system3. HIV virus and aids – we’ll cover it later in disease of blood and emergingdiseases
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