Transcript 1-overview
Immunology An Overview Learn on your own: Tolerance Clinical Immunology Self-Test Questions: A: 1 B: 1 - 4 C: 1 - 3 D: both E: 1 Overview of Immune System 1 Organization of the immune system Innate – less specific -- non-induced (e.g., skin) -- induced (e.g., inflammation) Adaptive (Acquired) -- more specific -- humoral (antibodies) -- cell mediated (T-killer cells) Responses are staggered Responses are coupled Overview of Immune System 2 What are the types of Innate Immunity? I. Non-induced mechanisms “Barriers to infection” -- 1st line of defense Anatomical Mechanical Cilia and mucus Skin wounding Overview of Immune System 3 Innate Immunity… II. Induced mechanisms Physiological, e.g., fever Cellular , e.g., phagocytosis Enzymatic, e.g., complement Receptor-mediated Broadly specific -- recognize “danger signals” Responses phagocytosis pathogen killing antigen presentation cytokine production http://lpi.oregonstate.edu/infocenter/phagocytosis.html Overview of Immune System 4 What are 4 characteristics of the Adaptive Immune system? Specificity Diversity Memory Self/nonself discrimination What are the two branches? Humoral Response: Attack free antigens via antibodies B-cell lymphocytes “B-cell receptors” (BCR) Cell-mediated Response: Hormonal regulation Attack infected cells T-cell lymphocytes “T-cell receptor” (TCR) AG on MHC proteins Overview of Immune System 5 What are the 2 principal types of T-cells? TH cells -- Helper-T, CD4+, T4 TC cells -- Killer-T, CD8+, T8 T-cell receptors of: TC cells to bind to type MHC-I TH cells bind to type MHC-II (CD4 and CD8 are called “coreceptors”) Annenberg Immune Responses Garland CTL attack Overview of Immune System 6 What are the two types of antigen-presenting cells? “Professional” AG-presenting cells “Non-professional” -- via MHC-I or MHC-II -- can present antigen to TH and TC cells Examples -- dendritic cells & -- macrophages -- B-cells -- (other IM cells) -- All nucleated body cells -- only present to Cytotoxic T-cells -- only via MHC-I -- response is cell destruction Overview of Immune System 7 Upon activation Naïve immune cells become Effector cells B-cells become: Plasma cells TH cells become: TH effector cells -- activate other cells Tc cells become: Cytotoxic lymphocytes (CTLs) Overview of Immune System 8 What happens when lymphocytes are activated? “Clonal Selection” Antigen recognition Cell activation Memory cells Immunological memory Primary vs Secondary responses Overview of Immune System 9 How do immune cells communicate? Extensive cell-cell contact Membrane protein interaction Immune synapse Hormonal exchange Cytokines Interleukins Interferons Chemokines etc Endocrine Paracrine Autocrine Overview of Immune System 10 Overview of Humoral and Cell-mediated Responses Cell meditated TH activated by AG presented on P-APC -- cytokines needed for TC and B-cell activation TC activated by DC cells & AG presented on infected cell -- kill target cells Humoral B-cells activated by free AG Ab bind to pathogens -- induce phagocytosis -- activates “complement” -- etc Overview of Immune System 11 Health lies in the balance the immune system achieves in its response to different antigens Response vs Tolerance Modulation of response Overview of Immune System 12