To reduce risks vaccines contain inactivated pathogens or their products Toxoid chemically modified exotoxin retains antigenicity but loses toxicity Killed bacteria cell formaldehyde heat Tetanus diphtheria Cholera made of dead fibriocholera cells Inactivated virus formaldehyde treated with some type of chemical so they are no longer active but our immune system will still respond to them Live cells virus more effective Salk polio vaccine influenza Attenuated has lost its virulence Tuberculosis weakened microbacterium so it still causes an immune response chickenpox attenuated chickenpox virus body still reacts so if you are exposed you will not get an infection Purified polysaccharide using parts much safer for everyone involved including developers and receivers Meningitis Immune system reacts to specific antigens Adaptive Immunity Retains memory of those antigens Humoral immunity Parts of foreign proteins sugars chemical Faster response if exposed a second time Production of antibody proteins o Each binds a different antigen Cellular immunity or cell mediated T cells that bind different antigens Kill pathogens and infected host cells control antibody Antigen presenting cell APC phagocytic cells that present Antibody immunoglobulin a soluble protein produced by B cells processed antigens to T cells type of white blood cell interacts with antigen production Most antibodies have Y shaped proteins The top of the Y is where the antibody will bind to an antigen The bottom part of the Y is where the antibody will attach to phagocytes and act as apopsis find correct word in last powerpoint Following ingestion of a pathogen phagocytes and B cell lymphocytes present antigens on their surface to T cell lymphocytes resulting in Cell mediated immunity T cells Antibody mediated humoral immunity antibodies and B cells o These two things are types of specific immune responses o Cell Mediated Immunity T cells Involves T cell lymphocytes white blood cells mainly used to protect against tumor cells Mainly protects against tumor cells and virus infected cells T cells are derived from bone marrow stem cells all cells are like These stem cells migrate to the thymus also mature here and this differentiate into the T lymphocytes only T cells do this Called T cells because of thymus Presentation of the Antigen When phagocytes digest pathogens polypeptides from pathogens are bound to the surface of a phagocyte Antigen Presenting Cell APC When an APC binds it causes the T cell to differentiate into lots of different T cells that will all recognize the same antigen Each T cell type can recognize the antigen that was presented to the original T cell Major Classes of T cells Helper T cells T H T H1 activate T c cells T cytotoxic T H 2 bind B cells and causing them to divide into plasma cells and memory cells Cytotoxic T cells T c releasing a poison Destroy tumor cells cancerous cells and infected cells by Also recognize grafted tissues and organs as foreign Allows host to respond to 2nd exposure to same antigen very Memory T M quickly o If memory T cells come in contact they will make many T cells to fight off antigen T cell Receptors Receptor attached to T cell surface membrane TCR Binds antigen specifically only to the antigen it was made to recognize Structure o 2 peptides and each with a constant and variable o variable domains bind antigen specifically domain MHC Proteins self proteins on the surface of cells Major Histocompatibility Complex bind to antigen antigen MHC is recognized by the T cell receptor Class I MHC proteins on surface of all nucleated cells presents Class II MHC proteins on surface of antigen presenting cells intracellular antigens to T c cells so infected cells can be destroyed by the T c cells phagocytes presents extracellular antigens to T cells bacteria or toxins in bloodstream or viruses that haven t entered yet to T helper cells T cells become activated when antigen MHC binds to T cell receptor Cell mediated Immunity T c cells destroy the antigen presenting cell or T H 1 cells recruit macrophages to destroy antigen bearing cells Tumor cells transplanted organs and tissues are attacked by T H 1 cell activated macrophages Antibody mediated Immunity Antibodies bind to antigens inactivate them Most active against bacteria bacterial toxins and viruses in the Also called humoral immunity bloodstream Role of Antibodies Antibodies don t recognize entire pathogen Recognize regions of antigens called epitopes Binding of antibody to a foreign cell does not directly kill the cell Antibody Binding Activates the complement system Enhances phagocytosis opsonization Causes agglutination Neutralizes antigens The Complement System group of proteins that act together to enhance immune system complement can o increase inflammation o attract and activate phagocytes o cause lysis o don t need to know details of picture on the right just know the overall picture Opsonization process of enhancing phagocytosis antibodies can bind both to a microbe and phagocyte simultaneously and bring them in closer proximity to each other antibody bridge increases ability of phagocyte to ingest microbe Antibody Structure and Diversity The 2 large heavy chains are identical and held together by 2 The 2 small light chains are also identical and held to the heavy see slide 20 for picture IgG consists of 4 polypeptide chains disulfide bonds chains by 1 disulfide bond the IgG molecule was made against The constant region of all IgG molecules is the same Variable regions where antigens bind Specific for the antigen that Each IgG can bind 2 antigens 5 Classes of Antibodies Immunoglobulins Heavy chain constant domains define class IgG IgA o Most abundant 80 of Ig in serum is IgG o Only antibody that can be transferred through the placenta o Gamma heavy chains this is where the G comes from o Picture above o Predominant antibody in secretions saliva tears breast milk o Dimer can bind to 4 antigens at the same time o Alpha heavy chains helps protect babies against infection mucus etc o IgM o 2nd most abundant Ig o 1st class of antibody made in response to infection o aggregate of 5 molecules attached by disulfide bonds and J o Can bind up to 10 antigens o Mu heavy chains chain protein o IgE o Low concentration responsible for allergies o Binding of antigen to IgE causes release of histamine allergies IgD to produce antibodies mostly IgG o Epsilon heavy chains o Made to protect against larger parasites o Found on the surface