pGLO Reflection What were we trying to do in this lab? Did we accomplish it? How do you know that the lab was/wasn’t successful? What were the controls used in this lab? What did they show us? What role did arabinose play in the GFP gene expression?

Microbiology Fighting Infections – a nod to AP and Immunity Biology 11H Microbiology Fighting Infections – a nod to AP and Immunity

Objectives By the end of the lesson you should be able to: Describe the levels of our immune system Describe the ways in which we fight back against an infection

Immune System The immune system is mainly comprised of lymphatic system and a population of White Blood Cells (WBC) called leukocytes that patrol the circulatory system

Immune System Overview We have 2 ways of fighting infections: Innate Immune System: “non-specific” broken down into 2 types External and Internal Adaptive Immune System: “specific” broken down into 2 types Humoral and Cell-Mediated

Innate Immune System Animals are the only organisms with a major immune system External: “barriers” SKIN: water-proof, sweat glands, “good” micro-organisms MUCOUS MEMBRANES: lined with mucus – sticks to pathogens, contains lysozyme – disrupts bacterial cell walls CILIATED MEMBRANES: contain cilia, works with mucus to trap and move pathogens Internal: phagocytes & inflammation PHAGOCYTES: WBCs that patrol circ system and “eat” anything that is foreign, present foreign pieces for specific response INFLAMMATORY RESPONSE: Mast cells at area of infection release histamine and call phagocytes to the infected area. Histamine also increases blood flow to the area ( = red/swelling/hot)

INFLAMMATORY RESPONSE

Adaptive Immune System The responsibility of the WBCs called lymphocytes that live in the lymphatic system. There are 2 types: B cells & T cells B Cells: born and raised in the bone marrow. Responsible for the HUMORAL response. T cells: born in the bone marrow but raised in the thymus gland. Responsible for the CELL-MEDIATED response.

Adaptive Immunity: Humoral Response Responsibility of the B cells Results in the production of antibodies SPECIFIC to the antigen of the invading pathogen STEPS: Phagocytes present antigens to Helper T cells Helper T cells activate B cells B cells produce different antigen receptors until the reactive one is made. This B cell is cloned. 4. The cloned B cell creates 2 types cells: Plasma cells and Memory B cells Plasma Cells: make and secrete antibodies to the circ. system Memory B Cells: circulate in the lymphatic system in case of future infection from same pathogen

So what?? Why antibodies??? Antibodies can cause 3 different responses when they’ve attached to an antigen Opsonization: tagged pathogens are “eaten” by macrophage Neutralization: tagged pathogens are unable to infect other cells Complement Activation: complement system forms pores in the cell membrane of tagged pathogen - LYSIS!! 

Adaptive Immunity: Cell-Mediated Response Responsibility of T cells Results in activation of T cells that recognize specific antigens STEPS: Phagocyte presents antigen to Helper T Cell Activated Helper T Cell activates specific T Cells Activated specific T Cells creates 2 populations of T Cells: Cytotoxic T cell and Memory T Cells Cytotoxic T Cells: find cells with specific antigen Memory T Cells: circulate lymphatic system in case of future infection by same pathogen Cytotoxic T Cells trigger death by secreting perforin (creates holes in pathogen’s cell membrane)