1. 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?

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

3. 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

4. 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

5. 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

7. 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)

8. INFLAMMATORY RESPONSE

9. 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.

10. 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

11. 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!! 

12. 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)