EX2 Immunology 1 Flashcards
What are the 3 key properties of the immune system?
- A diverse repertoire of antigen receptors (allowing for recognition of plethora of pathogens)
- Immune memory - rapid recall of immune responses
- Immunological tolerance - prevent immune damage to normal self-tissues
what is the immune system known as, it is one of the greatest _____
first and last lines of defense
one of greatest communication systems of the body
what does the immune system require
coordination between innumerable cells and molecules joining to defend against disease/ invading microorganisms
each component reacts w other components (cell to cell or via chemical mediators)
each cell/process must be understood as it relates to the maintanance of homeostasis
what is a pathogen, give examples
any organism that has potential to cause disease
bacteria, viruses, fungi, parasites ( also unicellular protozoa and multicellular worms)
What are the 3 roles of the Immune System?
- Defense against invasion (bacteria, viruses, foreign substances)
- Distinguish between self and invader
- Defense against abnormal cells/molecule formation in the body.
What is the most important function of the immune system?
Defending against infection by preventing infection and/or eliminating established infections.
what is the def of immune system
the collection of cells, tissues, and molecules that mediate the resistance efforts
what is immunity
the bodys ability to defend against pathogens/ foreign substances that cause disease
what is the immune response
coordinated reactions of those cells and molecules against infectious microorganisms
What are the two types of immunity and their differences?
Innate/Natural immunity is the first type of immunity and includes the skin and epithelial layers (physical sep from envmt), and our innate immunity.
Adaptive/Acquired immunity is the 2nd line of defense and is found only in vertebrates. It includes adaptive immunity and antigen specific immunity
what is adaptive/aquired immunity dependent on
influences from the innate immune system
when is the immune response initiated- what are the two players timing
immune response activated once the epithelial barriers are breached and pathogens enter the body
innate immunity gives initial protection
adaptive immunity gives a slower, more specialized response
what is the time of response, diversity, microbe recognition, principle immune cells involved, and memory of INNATE immunity
-time- immediate (minutes to hours)
-diversity- limited number of antigens recognized/groups microbes identified
- microbe recog- general patterns on microbes, NONSPECIFIC
- principle immune cells involved- granulocytes, monocytes/macrophages, natural killer cells, dendritic cells
-memory- NONE- responds same way to repeat encounters with the same pathogen
what is the time of response, diversity, microbe recognition, principle immune cells involved, and memory of ADAPTIVE (acquired) immunity
- time- delayed (days-weeks)
- diversity- large number of highly SELECTIVE antigens recognized
- microbe recog- SPECIFIC to individual microbes and antigens
- principle immune cells involved- B lymphocytes, T lymphocytes, dendritic cells, natural killer cells
- memory- YES- responds more effectively after each encounter with the same pathogen
what is hematopoesis
another term for hemopoiesis- formation of blood cellular components
all starts from hematopoietic stem cell
What is progenitor of the granulocytes and the lymphocytes?
Stem cells differentiate into lymphoid stem cells and myeloid orogenitors.
Myeloid progenitors differentiate into granulocytes(neut, eos, bas, mast, mono) while lymphoid stem cells differentiate into lymphocytes.
What cell types do lymphocytes differentiate into?
B cells, T cells, and NK cells.
what do B cells differentiate into
plasma cells and memory cells
what do T cells differentiate into
Th (T helper) and Tc (T cytotoxic killer cells)
what does innate immunity consist of
physical, chemical, cellular and molecular defenses that are ready for activation and mediate rapid, initial protection against infection
What are dendritic cells derived from?
Monocytes
What are the epithelial barriers of the body? what are the three categories and examples?
All portals of entry into our body (skin, GI, resp, urogenitla).
Includes:
- Mechanical/Physical: flow of fluids, mucus, saliva, urine, tears
- Chemical: sebum, enzymes, and lysozymes, acids, antimicrobial peptides
- Microbiological/Cellular: normal flora of skin, GI tract, resp tract, GU tract, and eyes.
What are the cells involved in our innate immune response?
Monocytes, macrophages, dendritic cells, NK cells, neutrophils, basophils, eosinophils, and mast cells.
what differentiation of a stem cell is innate immunity from (plus one exceoption)
myeloid progenitor - plus natural killer cells from lymphoid stem cells
What is % of WBCs is a monocyte?
It is 3-7%.
what are monocytes size and what are they a precursor to
they are the largest of all WBC
precursor to macrophages- when monocyte enters tissues they are called macrophages (sometimes given special names depending on location)
may also mature into dendritic cells
what is the first phagocyte microbes encounter when entering the host
monocyte-macrophages
What cells are not granulocytes in our innate immunity?
Monocytes,macrophages, dendritic cells and NK cells.
What are the immune functions of macrophages?
Clearing out bacteria that get past the epithelial barrier
Phagocytosis
Produce cytokines that help initiate inflammation and recruit other cells
Present antigens to T cells
Non-immune function: garbage disposal
What is the function of dendritic cells?
- Resides in the body’s tissues
- serves as cellular messengers that initiate adaptive immune response.
- present antigens to T lymphocytes (APC)
what type of cell initiates the adaptive immune response and how is it done?
dendritic cells
degrading pathogens from infected tissues and transport them to organs that specialize in synthesizing adaptive immune responses
what are NK cells
lymphocytic cells that functions in innate immunity
circulates in blood until needed in tissues
how do NK cells work?
doesn’t directly recognize pathogens via antigen receptors but has membrane receptors that recognize damaged cells (virus infected cells, tumor cells)
NK cells release contents of their granules that cause lysis or apoptosis to destroy target cells (can immediately kill cells without previous exposure)
Why are NK cells important?
They help limit the spread of infection via cytokine production.
why are NK cells called “natural”
because they are active without having been exposed to a virus previously
what are the amplifiers and effectors of the innate immune response
granulocytes of innate immunity (eosinophils, basophil, neutrophils)
What can the unchecked accumulation and activation of granulocytes lead to?
Host tissue damage, such as in systemic necrotizing vasculitis.
What is the most abundant WBC? Approx what percentage of WBC? Length of life?
Neutrophils, which consist of 55% of all WBCs.
They will degrade after a few days if not sent to site of bacteria infection
What kind of infection are neutrophils usually present in?
Bacterial infections.
how do neutrophils kill via phagocytosis
contain cytoplasmic granules with toxic substances that kill/inhibit bacteria and fungi +activate respiratory burst causing ROS to attack pathogens
What are the two ways neutrophils kill pathogens?
Phagocytosis with ROS.
NETs
What is ROS?
Reactive oxidative species, which uses free radicals to destroy all cells.
Neutrophils activate a respiratory burst that produces ROS to attack pathogens
What is a NET?
Neutrophil Extracellular Trap, which immobilize pathogens, facilitate phagocytosis, and directly kill pathogens.
What is the second most abundant granulocyte?
Eosinophils, which account for 1-4% of all WBCs.
What are the immune functions of Eosinophils?
Release granules containing toxic proteins, peroxidase, and hydrolases.
Display surface membrane receptors for IgE antibodies.
when are eosinophils recruited
recruited into tissues in response to large parasitic worm infections (helminths)
can also be associated with allergic responses
What is the rarest granulocyte in circulation and what percent is that? what do they respond to?
Basophils, which account for <1% of all WBCs.
respond to parasitic infections (go from blood into tissue)
what other granulocyte are basophils similar to and how?
mast cells except basophils circulate in blood until they are needed
What mediators can basophils and mast cells release?
Histamine and heparin
What additional mediator can a mast cell release that a basophil does not?
Lipid mediators to affect blood vessels and smooth muscle.
what are mast cells
- granulocyte found in tissues surrounding blood vessels
- granules contain bioactive amines (histamine) and lipid mediators
- important role in initiating inflammatory reactions
- display surface membrane receptors for IgE antibodies
what cell is responsible for sx related to immediate hypersensitivity (allergy)
mast cells
how do immune system players recognize self from non self
via use of and recognition of specific and molecular patterns and recognition receptors specific to different pathogens
DAMPs, PAMPs, PRRs, TLRs
What are PAMPs
Pathogen associated molecular pattern
-molecules shared by a number of pathogens that are not present on normal human cells (host cells)
- recognized by host cell PRRs of innate immune system
what are DAMPs
Damage associated molecular patterns
molecules released by damaged/dying cells recognized by some innate immune system cells
what are PRRs
pattern recognition receptors
innate immune cell receptors that recognize the PAMPs or DAMPs
what are TLRs
toll like receptors
PRRs that help regulate wound healing, tissue repair and regeneration
How do NK cell receptors work?
They have activating and inhibitory receptors. Healthy cells engage with the inhibitory receptors (via ligands), while damaged cells express stress molecules that trigger the NK activating receptors to overpower the NK inhibitory receptors