N5315 Advanced PathophysiologyImmune SystemPrerequisite Knowledge Objectives with AdvancedOrganizers1

N5315 Advanced Pathophysiology Immune System Prerequisite Knowledge Objectives with Advanced Organizers 1. Examine the structure and function of the immune system. a. Describe how the normal function of T-lymphocyte and B-lymphocyte cells differ. Background: P. 225-226 Each individual T or B cell specifically recognizes only one particular antigen, but the sum of the population of lymphocytes specificities may represent millions of foreign antigens. This process is called the generation of clonal diversity and occurs in specialized (primary) lymphoid organs—the Thymus for T cells and bone marrow for B cells. While passing through these tissues, the lymphocytes mature and undergo changes that commit them to becoming either B or T cells. Lymphocytes are released from these organs into the circulation as immature cells that have the capacity to react with antigen (immunocompetent) These cells migrate to other (secondary) lymphoid organs in the body in preparation for exposure to antigen. The lymphocytes remain dormant until antigen initiates the second phase of the immune response, clonal selection. This process involves a complex interaction among cells. To initiate an effective immune response, most antigens must be “processed” b/c they cannot react directly with cells of the immune system but must be shown or “presented” to the immune cells in a very specific manner. This is the job of antigen-processing (antigen-presenting) cells, generally referred to as APCs. In general, three groups of cells must cooperate to make an immune response. The APCs interact with subpopulations of T cells that facilitate immune responses (T helper cells), and immunocompeten