Lecture 1: Intro Flashcards
Advantage and disadvantage of innate system
ADVANTAGE: instantaneous activation
DISADVANTAGE: lack of specificity to target pathogens
Advantage and disadvantage of adaptive system
ADVANTAGE: memory and specificity
DISADVANTAGE: slow (over a week to become operational)
Innate system ________ of pathogen to infect host; adaptive _________ pathogen
delays ability
eliminates
Two barriers to infection (first line of defense in innate immunity)
1) Skin
2) Mucosa
Name of chemicals produced by skin to fight off pathogens
defensins
Mechanisms by which mucosa protects against invaders
1) mucus traps pathogens
2) cilia beat and eject particles out
3) tears and saliva produce hydrolytic enzymes to kill bacteria
Three classes: mechanical, chemical, microbiological
What two systems developed their own REGIONAL immune system?
gut and lung
Second line of defense in innate immunity:
group of rapidly mobile cells that can go to site of infection and kill pathogen
What are the two signals these cells respond to?
1) PAMPS (pathogen associated molecular patterns)
2) DAMPS (damage associated molecular patterns)
How, molecularly, do these innate cells recognize PAMPS and DAMPS?
Via the pattern recognition receptors (PRRs):
1) TLR: Toll-like
2) RLR
3) NLR
What functionally serves as the “on” switch for an innate immune response?
activation of TLR
What are the 2 pathways used by innate system to neutralize threat?
1) soluble proteins made in the liver (mannose binding receptor, serum proteins in the complement system)
2) immune effector cells
What are the 2 types of proteins the liver makes to support the innate system?
1) Mannose binding receptor - circulates in the plasma, binds to mannose containing structural components of bacterial cell walls. Activation of this phagocytoses bacterium
2) serum proteins known as the complement system
What is known as the ancestral precursor of the antibody?
Mannose binding receptors (identify bacteria and phagocytose it)
What are the main cells of the innate immune system?
leukocytes
What is the main hallmark of leukocytes?
granules - contain lots of killer molecules that, when released, destroy the bacteria
Do leukocytes of the innate system remember their encounters with pathogens?
NO but they can be primed to react more vigorously during a subsequent encounter
What are the 5 classes of leukocytes?
1) Neutrophils
2) Eosinophils
3) Basophils and Mast cells
4) Monocytes/Macrophages
5) Dendritic cells
Most common leukocyte:
neutrophil (final arbiter in most inflammatory reactions)
Function of eosinophils:
respond to parasitic infections
Function of basophils:
least common leukocyte; serve as antigen presenting cells (have specialized granules/receptors that are important in specialized antibody reactions)
Function of macrophage:
eat bacteria
Function of dendritic cells:
sentinel cells of immune system and critical to activate adaptive system
very rich in TLRs and continually sample the environment for DAMPs and PAMPs
What are the innate lymphoid cells?
1) Natural Killer Cells
2) gamma delta lymphocytes and NKT lymphocytes
What are the main features of natural killer cells?
they have large granules (but are not granulocytes); they constantly sample the environment like dendritic cells, can recognize DAMPs and PAMPs
Which molecular family facilitates communication with the innate immune system?
cytokines
What is the molecular make up of cytokines?
two peptide chains encoded by separate genes
Over time, evolutionary pressures drove cytokine systems to develop:
1) families
2) pleiotropism
3) redundancy
True or false: cytokines are only produced after stimuli
true
Which cells express cytokines?
immune and non-immune cells
Cytokines serve as the __________ of cellular communications that provide the critical links in humoral (antibody-mediated) and cellular mediated immunity
mediators
Cytokine production, release, and receptor display allow for which type of important communication?
antigen-specific immune effector cells (lymphocytes) and non-antigen specific counterparts (macrophages and dendritic cells)
Which two features of cytokine receptors tailor the level of intensity of the immune response?
1) density
2) affinity
Antigens can be viewed as evolutionary refinement of ______
PAMPs
How does the adaptive immune system generate a highly efficient immune response?
clonal amplification
What are the cells of the adaptive system?
1) Macrophages and dendritic cells - (now have new roles - uptake and processing of pathogens, present foreign matter to other cells)
2) small lymphocyte - generates specific antigen receptors on surface, communicates with other cells, proliferates in response to the antigen and amplifies a targeted lethal response by producing killer cells or antibodies
What are the two groups of adaptive lymphocytes?
1) B cells
2) T cells
What cells mediate the humoral immune response?
B cells (produce antibodies and ultimately differentiate into plasma cells)
What are the two main functions of the T cells?
1) HELP orchestrate the immune response
2) KILL harmful pathogens
What cells mediate the cell-mediated immunity?
T cells (good at targeting infections that hide inside host cells)
What are the 3 effector molecules of the adaptive system?
1) Complement system (enzymes that amplify innate response)
2) B cells (clonally amplify adaptive response)
3) Cytokines
