BIOL 244 1st Edition Lecture 5Outline of Last Lecture I. Innate vs. Adaptive Immune System II. Humoral Immune ResponseIII. 2 Ways to Acquire Humoral Immunity IV. Antibodies in Humoral Immune Response V. Cell-mediated Immune Response Outline of Current Lecture I. Cell-mediated Immune Response II. Major histocompatibility (MHC) proteinsIII. T-cell ActivationIV. Helper T-cellsV. Regulatory T-cellsVI. Cytotoxic T-cellsVII. Organ TransplantsCurrent LectureI. Cell-mediated Immune Response (Cellular immunity)a. Connected to humoral immunityb. Antibodies cannot defend against things that are inside cellsi. Only functional against antigens that are present in extracellar environmentii. T-cells are capable of detecting antigens that are hiding within your cells These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. Cellular immune system has to be able to distinguish between antigens that belong in your body and antigens that are foreign to the body i. Must learn to recognize and ignore self-antigens d. T-cellsi. 2 major types1. CD4: Have CD4 proteina. Can create CD4 cells, memory cells, helper T-cells (TH), regulatoryT-cells (TReg)2. CD8: Have CD8 proteina. Can create CD8 cells, cytotoxic cells (TC), memory T-cells ii. Have to recognize the joining together of self-antigens and non-self antigens iii. Have more complicated antigen-binding than B-cells II. Major Histocompatibility (MHC) Proteinsa. Molecules/proteins found on the surfaces of all of your cellsi. The more closely related you are to someone, the more similar your MHC proteins are (the more distantly related-the more different)ii. Self-antigens b. Play a role in who females choose to have sex withi. When women are ovulating they are attracted to the MHC protein in men that is different from theirs c. Class I and Class IIi. Class 1: present on surfaces of all cells 1. Recognized by CD8 T-cells2. Include viruses, parasites, (route other than phagocytosis)3. Displayendogenous antigens on the surface of the cella. Something derived from inside the same cell that the protein is on the surface of b. Protein presenting bits of normal cell parts: self-antigensi. Will be ignored by T-cellsc. Protein presenting pieces of a cell that has been invaded by virus: non-self antigensi. Can trigger an immune response4. Cancerous Cellsa. Abnormal molecules producedi. Abnormal bits displayed by protein: non-self antigen (because it’s abnormal)ii. Class 2: found on antigen presenting cells1. Dendritic cells, macrophages, B-cells2. Recognized by CD4 T-cells 3. Display exogenous antigens a. An antigen that was engulfedi. The antigen presenting cells are engulfing things that are outside the cell and breaking them downii. Class II proteins present these bits on the surface III. T-cell Activationa. Huge population of immunocompetent but naïve T-cellsi. In order to be activated, antigen receptor has to bind to both antigen and MHC protein b. Antigen bindingi. T-cell antigen receptors (TCRs) get T-cell ready so it has the ability to bind1. There are receptors on the surface of T-cells that are specific to an antigen2. T cells only bind to antigens that are presented by MHC proteins a. Have to recognize the non-self antigen and self antigen b. Do not recognize random antigens 3. After binding, T-cell has the ability to proliferate and form a cloneii. Co-stimulation prompts the T-cell to actually divide1. T-cell binds to other receptors on the antigen-presenting cell a. Stimulates it to release chemicals that can provide co-stimulation 2. Sometimes it’s the T-cell that is releasing chemicals to provide co-stimulation 3. Sometimes there is a third cell that released chemicals and stimulates the T-cellIV. Helper T-cellsa. Enhance antibody-mediated immunity i. A good response requires helper t-cells (but can still happen without)ii. Influences B-cells to divide more quickly b. Function in cellular-mediated immunity i. Involved in activation of immunocompetent cellsii. Binds to the non-self antigen being presented by MHC protein 1. Co-stimulation chemicals released by helper-t cellV. Regulatory T-cellsa. Dampen immune responsei. Help prevent auto-immune disordersVI. Cytotoxic T-cellsa. The only immune cells that are capable of attacking and destroying other cellsb. Release perforin and granzyme moleculesi. Perforin: perforate the membrane of the target cell1. Creates an entry way for granzymesii. Granzyme: enter target cell and can stimulate reactions that lead to apoptosis/cell deathVII. Organ Transplants a. Autograftsi. Own tissue is transplanted from one part of body to another1. Example: Self-donating bloodii. Not going to cause problems (self-antigens)b. Isograftsi. Transplant tissue/organs between individuals who are genetically identical1. Example: Sibling who is an identical twin has same genes (same antigens)ii. Not going to cause problems (self-antigens)c. Allograftsi. Transplant from someone who is not genetically identicald. Xenograftsi. Transplant from another species1. Example: Pig heart