Chapter 22 - Immunity Lecture 2 Adaptive Immunity PDF

Part 1: Introduction to Adaptive Immunity, Its Main Characteristics, and the 4 Types of T-Cells. Part 2: Antigen Presentation, T-Cell Activation, and Functions of Each T-Cell   Immunity that develops after exposure to specific antigen (specific immunity). 2 main TYPES: Cell-mediated – defense agai...

Part 1: Introduction to Adaptive Immunity, Its Main Characteristics, and the 4 Types of T-Cells. Part 2: Antigen Presentation, T-Cell Activation, and Functions of Each T-Cell   Immunity that develops after exposure to specific antigen (specific immunity). 2 main TYPES: Cell-mediated – defense against abnormal cells & pathogens INSIDE cells. Lymphocyte? ◦ T-cells  Humoral (Antibody-mediated) immunity – defend from antigens + pathogens in fluids. Lymphocyte? ◦ B-cells which become plasma cells.  Born with innate; must acquire or induce adaptive immunity. ◦ Occurs in a variety of methods (22.16). ◦ How does one acquire/induce immunity?  Active immunity (AI) = exposure to pathogen ◦ Naturally acquired AI = environmental exposure. ◦ Artificial induced AI = controlled conditions/vaccine  Passive immunity (PI)= no exposure to pathogen. ◦ Naturally acquired PI = breast milk ◦ Artificially induced PI = receiving antibodies (injection)  1) Specificity = recognize specific antigens ◦ ignore others.  2) Versatility = produce diff. lymphocyte populations (millions) to target specific antigen. ◦ Population #’s of a specific, activated-lymphocyte leads to production of clones.  3) Memory = initial exposure leads to memory cells ◦ Circulating cells that trigger stronger immune response to 2nd exposure.  4) Tolerance = avoid destroying “self” antigens. ◦ B or T-cells that attack “self” antigens are destroyed.  Failure of tolerance results in? ◦ Autoimmune disorder  Specialized “warriors” for adaptive immunity. ◦ 20 – 40% circulating; 1 trillion in lymph organs.   1) T cells (thymus dependent) = cell-mediated immunity + stimulates immune response 2) B-cells (bone marrow) = antibodies (immuno.)  NK-cells attack cancer cells; functions in immunological surveillance, considered an innate lymphocyte, use perforins  1) Cell mediated immunity; key points? ◦ Antigens w/in cells, T-cells finish maturation where? ◦ finish @ thymus become Thymocytes = Immature Tcells – 95% undergo apoptosis & then phagocytized  2) Humoral (antibody) mediated? ◦ Antigens in fluids; B-cells finish maturation? ◦ In red bone marrow, when activated, become? ◦ Plasma cells – secrete antibodies   Diff. tissues have diff conc. of T- + B-cells. Lymphocytes are NOT permanent residents; ◦ They wander through tissues  The process that produces lymphocytes? ◦ Lymphocytopoiesis via 2 lymphoid stem cells.  Group 1 stem cells (remain in bone marrow) differentiate into B and NK cells. ◦ stromal cells produce Interleukin-7 that stimulates Bcell differentiation.  Group 2 stem cells migrate to thymus, where which hormone triggers differentiate to T cells? ◦ Thymosins ◦ T-cell move faster throughout tissues!   1) Cytotoxic T-cells (TC Cells) = cell mediated immunity via direct attack of antigens. 2) Memory T cells = are? ◦ Cloned version after initial response that elicit strong secondary response on a “remembered antigen.”   3) Helper T cells (TH cells) = stimulate the function of B and Tcells. 4) Regulatory T cells (TRegs cells) = inhibit function of T and B cells, important for? ◦ Important for tolerance. Part 1: Introduction to Adaptive Immunity, Its Main Characteristics, and the 4 Types of T-Cells. Part 2: Antigen Presentation, T-Cell Activation, and Functions of Each T-Cell Part 1:  Differentiate the various innate white blood cells!  Define adaptive immunity and differentiate among the 2 types: cell-mediated vs humoral.  Differentiate between the 2 types of active and 2 types of passively acquired immunity.  Describe the 4 characteristics of adaptive immun.  Identify, describe, and differentiate the 4 types of Tcells. Part 2:  Identify and differentiate between the 2 MHC complexes and relate this to antigen presentation.  Differentiate the 2 types of CD markers, and identify the T-cells that have either CD4 vs CD8.  Identify, describe, and explain the effects of CD4 and CD8 T-cell activation, and differentiate regulatory vs memory T-cells.    = cells (infected or APCs) put foreign antigen into glycoprotein & put it on OUTER surface of cell. Requires T-cell receptors (TCR) – receptors on Tcells that bind antigen-glycoprotein combo of infected cell activating the T-cell. Glycoproteins that bind antigens & signal T-cell = Major Histocompatibility Complex (MHC). ◦ MHC differ (genetically) amongst individuals; this complicates transplants.    There are 2 classes (activate diff. T cells): MHC Class 1 = PMs of ALL nucleated cells; presented on infected cells (viral + bacterial). MHC Class 2 = PMs of Antigen Presenting Cells (APCs); (mainly phagocytes).  MHC1 = Infected cell; 2 = APC via 2 ways.   1) Phagocytes destroy & present antigen on surface (most common) 2) APCs find foreign antigen and present on surface w/out breakdown of antigen.  aka CD (cluster of differentiation) Markers = T-cell membrane co-recognition proteins for MHCs. ◦ Diff. CD markers = diff. responses to MHCs.   CD Markers = another way to “name” a cell: CD8 Markers – respond to antigens via MHC1 ◦ Found on cytotoxic T- and regulatory T-cells.  CD4– respond to antigens bound to MHC2 (APCs) ◦ Found on helper T-cells.   T-cells that have NOT found an antigen = naïve Tcells = inactive. After exposure to antigens, T-cells go from naïve T-cells to activated T-cells.    A) Perforin – destroys plasma membrane resulting in an inability to regulate exchange. B) Cytokine – chemical signal that stimulates apoptosis. C) lymphotoxin release – disrupts metabolism   Cells that stay in circulation for a 2nd response. Activation is quicker + stronger response. ◦ May not even feel symptoms. ◦ First time TC activation is slow.  Treg-cells that are produced in low #’s. ◦ secrete suppression factor that inhibits/suppresses responses of T + B cells. ◦ Moderate activities of T- and B-cells ◦ Important after infection ends   TH-cells bind to MHC2 complex found on APC cells (likely phagocytic). Once activated, secrete cytokines? that stimulate B- and TC- cells. ◦ Chemical messengers that coordinate cell activity.      Cytokine (Helper T-cell) functions include: 1) Promote B-cell activation. 2) Attract + stimulate macrophages. 3) Attract + stimulate activity of TC-cells 4) Stimulate T-cell division ◦ Produce memory TH cells? + accelerate cytotoxic T cell maturation. ◦ Stronger + quicker 2nd response to same antigen.