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Transcript
The Immune System I. Specific Immunity A. Humoral Mediated: (B-Cell immunity; Free Ig’s) Antibodies react to bacteria by: 1. Binding directly with bacterial toxins to neutralize them 2. Coat bacteria to enhance the phagocytosis be non-specifics components (monocytes, etc.,). Immunoglobulin subclass: IgG, IgA, IgM, IgD, & IgE The Immune System I. Specific Immunity B. Cell Mediated: ( T-cell immunity; membrane receptors) Viruses, parasites, fungi, etc., are reacted by: 1. Helper - T 2. Cytotoxic - Tcells 3. Macrophages 4. Tranfer factor 5. Cytokines (lymphokines/interleukins) II. Non-specific Immunity Table 15.2 Phagocytic Cells and Their Locations Phagocyte: Neutrophis Monocytes Tissue macrophages (histiocytes) Kupffer cells Alveclar macrophages Microgia Location: Blood & all tissues Blood & tissues All tissues ( including spleen, lymph nodes, bone marrow) Liver Lungs Central nervous system Development of the Immune System Yolk sac/Bone Etrythrocytes Granulocytes Hematopoietic stem cells Monocytes Megokaryocytes Lymphoid stem cells Bone B-lymphocytes Plasma cells Humoral Immunity Thymus T-lymphocytes Sensitized lymphocytes Cellular Immunity Immunology Review Antigen macrophage Immune System Transfer factor Delayed hypersensitivity T-cells Cellular thymus Advanced lymphcytes B-cells Humoral Bone (Gut associated lymphoid tissue) Plasma Cells Immunoglobulins (immediate hypersensitivity) Table 15.5 Immunology Review Immunoglobulins IgC most abundant Ig of internal body fluids, particularly extravascular. Where they combat micro-organisms and their toxins IgA major Ig insero-mucus secretions where it defends external body surfaces IgM very effective agglutinator; produced early in immune response - effective first line of defense vs. bacteraemia IgD present on lymphocytes surface of newborn IgE raised in parasitic infections. Responsible for symptions of atopic allergy Table 15.5 Immunology Review Immunoglobulins Antibody model proposed by R.E. Porter with two heavy and two light polypeptide chains held by interchain disulphide bonds light X Antigen binding sites S S heavy S S heavy X light S S Birth IgM % Adult Level 100 IgG 50 IgA, IgD, IgE 0 -3 0 Infant 6 12 18 Mother Age in months Development of serum immunoglobulin levels in the human. The Complement System Mechanism of Action 1. IgG & IgM-antigen complexes bind with C-1 to activate the enzyme system. 2. Activated C-1 converts C-4 into C-4a & C-4b. 3. C-4b binds to the antigen’s membrane (is fixed) and causes theconversion of C-2 into C2a & C-2b. 4. C-2a attaches to C-4b and causes the cleaving of C-3 into C-3a & C-3b. The C-3b attaches to the complex while C-3a is secreted. The Complement System Mechanism of Action 5. Activated C-5 through C-9 become fixed to the antigen & create large pores in the membranes of the antigens allowing H20 influx. The cells (bacterial) swell and burst. 6. C-3a & C-5a produce chemotaxic substances which: A) attract phagocytes B) cause opsonization-stimulates phagocytes C) cause release of histamine from mast cells The Complement System (continued) Summary 1. Recognition: (C-1) 2. Activation: (C4, C2 + C3) 3. Attack: (C5 -C9) Development of the T-cell System Lymphocyte precursors originate in the yolk sac and migrate into the fetus. The lymphoid stem cells then migrate to the thymus under the influence of an “attraction factor.” The cells then become “programmed” and become immunocompetent. PUTATIVE PROCESS: 1. Thymic hormones thyopoietin I & II transform the stem cells into T-cells in the thymic cortex 2. Thymic hormone thymosin promotes the maturation of T-cells in the thymic medulla & other lymphoid tissue. 3. Some of the T-cells enter the blood and travel to other lymphoid tissues and establish colonies (germinal centers) where they divide by clonal growth. Helper T-cell CD4 coreceptor Antigen presenting cell Killer T-cell T-cell receptor Foreign antigen Class-2 MHC molecule Class-1 MHC molecule CD8 coreceptor Target cell Figure 15.18 Coreceptors on helper and killer T cells . A foreign antigen is presented to T lymphocytes in association with MHC Molecules. The CD4, on helper T cells and CD8 corecepters on killer T cells, permit each type of T cell to interact only with a specific class of MHC molecule HIV life cycle: Viral Infection Free Virus Attachment Penetration CD4 Viral RNA Reverse transcriptase Proviral DNA Reverse Transcription Cell Nucleus Cellular DNA Integration HIV life cycle: phase of viral expression Free Virus Budding Packaging Viral proteins translation Genomic RNA splicing Cell Nucleus Viral RNA Transcription Proviral DNA Acquired Immune Deficiency Syndrome (AIDS) Caused by Human Immunodeficiency Virus (HIV) Classes: 1. Oncornaviruses (cause tumors, but not AIDS) a. HTLV-1 b. HTLV-2 2. Cytopathic Virus (Lenti-viruses) cause AIDS a. HIV-1 worldwide b. HIV-2 less pathogenic (geographically restricted) Acquired Immune Deficiency Syndrome (AIDS) (continued) Modes of transmissions: 1. Sexual contact with an HIV-infected person 2. Transfusion of HIV contaminated blood 3. In utero from infected mother to baby 4. Injected drug use 5. Mucocutaneous exposure (one case from kissing) Acquired Immune Deficiency Syndrome (AIDS) (continued) Risk of HIV Transmission: A person is at risk of HIV infection anytime s/he comes into contact with the following fluids of an infected individual: Blood Semen Vaginal fluid Breast milk Table 1 Body Fluids to which Universal Precautions Apply In Relationship to “Bloodborne” Pathogens Blood Serum/plasma Semen Vaginal secretions Cerebrospinal fluid Vitreous fluid Human Breast Milk Synovial fluid Pleural fluid Pericardial fluid Peritoneal fluid Amniotic fluid Wound exudates Table 2 Body Fluids to which Universal Precautions Apply If Containing Visible Blood In Relationship to “Bloodborne” Pathogens Saliva Feces Vomitus Urine Nasal secretions Sputum Sweat Tears Table 3 Handling of Medical Devices / Equipment for Reuse Method of Reprocessing: Use of Device: Decontaminate only use intermediate Contact with skin or low-level germicide or simple wash with soap and water Decontaminate, then preferably Contact with sterilize at a minimum do high level mucous disinfection by soaking 10 - 20 membrane minutes in an EPA approved chemical agent Penetrate skin Decontaminate and sterilize by cold sterilization (12) or preferably by heat steam or gas following the recommendations of the sterilizer Florida HIV Statistics as of 1/1/95 U.S.A. 1 in 250 est. to be HIV+ FLA. 1 in 100 est. to be HIV + Dade 1 in 40 est. to be HIV+ Orlando 1 in 20 est. to be HIV+ HIV leading cause of death among women aged 15 - 25 in USA 1 women infected every 1 -2 minutes Worldwide 1 women dies due HIV every 2 minutes AIDS/HIV Statistics as of 1/1/95 18,000 children have lost their mothers to HIV # of teens contracting HIV doubles every 14 months 6,500,000 teenagers contract a STD in USA each year 30,000 HIV infected teens in USA 1/1/94 FLA is: #1 Heterosexual trasnsmission #2 Injectable drug transmission #2 Teenage & pediatric cases #3 Total AIDS cases AIDS/HIV Statistics as of 1/1/95 AIDS leading Counties Cities Dade 13,654 Miami Broward 6,909 Ft. Lauderdale Palm Beach 3,775 West Palm Beach Hillsborough 2,585 Tampa Duval 2,225 Jacksonville Orange 2,249 Orlando Total cases 43,242 Fla 401,749 USA Characteristics of Lymphokines B-cell: Ig helper effect RNA or Thymic hormone Lymphokine B-cell: No Ig Suppressor effect T-cell: Blastogenesis Lymphokine Lymphokine Macrophage: Activiated marcophage Macrophage migration inhibition Chemotoxis Other cells: Viral resistance Cytotoxic inactivation