A course on Basic Immunology,with emphasis on immunologic diseases and therapeutic strategies Abul K. Abbas, Hidde Ploegh and Caetano Reis e Sousa Course schedule • 9:00. Overview Abul Abbas • 9:15. Innate immunity Caetano Reis e Sousa • 10:15. Coffee break • 10:30. Antigen presentation Hidde Ploegh • 11:30. T cell activation Abul Abbas • 12:30. Lunch • 2:00. T cell subsets Abul Abbas • 3:00. B cells Hidde Ploegh • 3:45. Break • 4:00. Tolerance and autoimmunity Abul Abbas Themes of the course • Introduction to the nomenclature of immunology • Basic principles: mechanisms underlying immune responses • Emerging concepts, and their potential clinical and therapeutic implications What does the immune system do? • Defense against infections • Defense against some tumors • Barrier to transplantation, gene therapy • Cause of disease (“immune-mediated inflammatory diseases”) Innate immunity: always present (ready to attack); many pathogenic microbes have evolved to resist innate immunity Adaptive immunity: stimulated by exposure to microbe; more potent Cells of the immune system • Lymphocytes: the cells of adaptive immunity; recognize antigens and develop (differentiate) into cells that perform the defense functions • Antigen-presenting cells: cells that capture antigens and display them to lymphocytes • Effector cells: leukocytes (white blood cells) that eliminate microbes (the “effect” of the immune response); may be lymphocytes, but are often other leukocytes Capture and presentation of antigens Dendritic cells are specialized antigen-presenting cells (APCs) that pick up and display proteins for recognition by T lymphocytes. Antigens are transported to lymphoid organs (e.g. lymph nodes) where adaptive immune responses are initiated Classes of lymphocytes Helper T cells are master controllers of immune responses The CD nomenclature for lymphocytes and other cells The humoral immune response: activation of B lymphocytes and production of antibody Rapid proliferation of antigen-specific lymphocytes (keeps pace with replicating microbes), e.g. 1 B cell --> 4,000 Ab-secreting cells --> >1012 antibody molecules/day Differentiation: generation of Ab secreting cells Cell-mediated immunity: T cell activation Activation of CD8+ T cells follows a similar sequence Cytokines • Secreted proteins that mediate immune and inflammatory reactions, and communications among leukocytes and other cells (“interleukins”) • Actions of a cytokine are most often autocrine (on cell that produces it) and paracrine (on neighbors), rarely endocrine (distant) A summary of adaptive immune responses The immune system can cause disease • Normal immune responses are induced by and defend us against infectious pathogens • Immune responses can be inappropriately induced and may cause injury to normal tissues, resulting in disease – The mechanisms of tissue injury are the same as the mechanisms that eliminate microbes.