Adaptive (Acquired) Immunity (3rd line of defense)Adaptive/Acquired ImmunityAdaptive ImmunityActive vs. Passive ImmunityRecognition and ResponseAntigensAntigen PresentationSlide 8TransplantationSlide 10CD1Antigen RecognitionAntibodiesSlide 14Slide 15Immunoglobulin G (IgG)Immunoglobulin A (IgA)Immunoglobulin M (IgM)Immunoglobulin D (IgD)Immunoglobulin E (IgE)Antibody StructureSlide 22Antigen BindingB Cell Receptor ComplexT Cell Receptor ComplexGeneration of Clonal DiversityClonal SelectionT Cell MaturationAntigen Processing and PresentationSlide 30Slide 31Helper T LymphocytesSlide 33Slide 34B Cell ActivationPrimary and Secondary ResponsesSlide 37Class SwitchB Cell Clonal SelectionT Cell ActivationSlide 41Superantigens (SAGs)Antibody FunctionSecretory (Mucosal) Immune SystemSlide 45IgE FunctionSlide 47Cell-Killing MechanismsSlide 49Other CellsFetal and Neonatal ImmunitySlide 52Aging and Immune FunctionAdaptive (Acquired)Immunity (3rd line of defense)Chapter 7Adaptive/Acquired ImmunityAntigens – Anything that cases a biological immune response by this system of cellsSpecificity – Some antibodies are quite specific to an antigen others are general to a “type” or “form”Memory – b-memory cells are formed and remain to combat future exposures quickly (Active vs Passive immunityAntibodies – the proteins formed by b-cells that combat antigens whether chemical or biologicalLymphocytes – cells involved in this responseAdaptive ImmunityClonal diversityProduction of T (Killer cell mediated response) and B lymphocytes (humoral/antibody response)Antigen recognition – zone of attachmentLymphocyte specificity – Classes of ImmunoglobulinsClonal selection – CD cluster recognition table 7-2Antigen processing – Recognition and binding depend on size of molecule/cell/tissue/organism and classCellular interactionActive vs. Passive ImmunityActive immunityAntibodies or T cells produced after either a natural exposure to an antigen or after immunizationPassive immunityPreformed antibodies or T lymphocytes are transferred from a donor to a recipientRecognition and ResponseRequired for a successful immune responseClusters of differentiation (CD)Originally used to describe proteins found on the surface of lymphocytesNow it is a labeling system used to identify a family of proteins on many cellsAntigensImmunogens vs. antigensAntigenic determinant (epitope)Self-antigenToleranceCentral and peripheral toleranceMolecular sizeHaptensAllergensAntigen PresentationAntigen-presenting cells (APCs)Major histocompatibility complex (MHC)Glycoproteins on the surface of all human cells (except RBCs)Also referred to as human leukocyte antigens (HLAs)MHC class I moleculesA, B, and CMHC class II moleculesDR, DP, and DQMHC class III moleculesAntigen PresentationTransplantationCells in transplanted tissue from one individual will have a different set of MHC surface antigens than those of the recipient Therefore, a recipient can mount an immune response against the foreign MHC molecules HaplotypeCombination of A, B, C, DR, DQ, and DP allelesTransplantationCD1Antigen-presenting moleculesFound on antigen-presenting and thymus cellsPresent lipid antigensAntigen RecognitionAntigen is directly recognized by circulating antibody, antigen receptors on B cells (BCR), and T lymphocytes (TCR)AntibodiesAlso called immunoglobulinsProduced by plasma cells Classes of antibodyIgG, IgA, IgM, IgE, and IgDCharacterized by antigenic, structural, and functional differencesAntibodiesAntibodiesImmunoglobulin G (IgG)Most abundant class (80%-85%)Transported across the placentaFour classes IgG1, IgG2, IgG3, and IgG4Immunoglobulin A (IgA)Two classes IgA1 molecules are found predominantly in the bloodIgA2 molecules are found predominantly in normal body secretionsIgAs found in body secretions are dimers anchored by a J chain and a “secretory” pieceSecretory piece may function to protect IgAs against enzyme degradationImmunoglobulin M (IgM)Largest of the immunoglobulinsPentamer stabilized by a J chainFirst antibody produced during the primary response to an antigenSynthesized during fetal lifeImmunoglobulin D (IgD)Limited information on IgD functionLow concentration in the bloodLocated primarily on the surface of developing B lymphocytesFunction as one type of B cell antigen receptorImmunoglobulin E (IgE)Least concentrated of the immunoglobulin classes in the circulationMediator of many common allergic responsesDefender against parasitesAntibody StructureAntigen-binding fragment (Fab)Recognition sites (receptors) for antigenic determinantsCrystalline fragment (Fc)Responsible for biological functionPolypeptide chains (4)Light chains (2) and heavy chains (2)Antibody StructureHinge regionConstant and variable regionsComplementary determining regions (CDRs)Framework regions (FRs)Antigen BindingAmino acid sequences of the variable regions of the heavy and light chainsFramework regions control antibody foldingLock and keyNoncovalent chemical interactionsAntibody valenceIgG, IgD, and IgE—2IgA—4IgM—theoretically 10, likely 5B Cell Receptor ComplexLocated on surface of B cellsConsists of:Antigen-recognition molecules Monomer IgM and IgD Accessory intracellular-signaling moleculesIg-alpha and Ig-beta heterodimersT Cell Receptor ComplexAntibody-like transmembrane protein (TCR)Accessory proteins for intracellular signaling Referred to as CD3Generation of Clonal DiversityAll necessary receptor specificities are producedTakes place in the primary (central) lymphoid organsResults in immature but immunocompetent T and B cellsPrimarily occurs in the fetusClonal SelectionImmunocompetent T and B cells migrate from the primary lymphoid organs to the secondary lymphoid organs to await antigenPrimarily after birthClonal selection is initiated by antigenFinal productsPlasma cells that produce antibody, effector cells that help Th, Tc, or Treg, and memory B and T cellsT Cell MaturationThe thymus is the central lymphoid organ of T cell developmentT cells move from the thymic cortex to the medullaChangesDevelopment of the T cell receptors and expression of surface moleculesT cells are released into the blood and take