____ immunity is always present in healthy individuals, is the first responder (has a rapid response), block entry of microbes, kills microbes that enter, and sends signals to alert adaptive immunity.
What are 5 things that innate immunity cannot/does not do?
1. does not recognize specific antigen structure
2. does not require prior exposure to antigen
3. does not become stronger (it will have the same reaction every time it encounters a pathogen)
4. does not react against noninfectious foreign substances or self-molecules/cells
5. does not form memory cells
What are 4 examples of epithelial barriers?
skin, respiratory mucosal epithelia, GI tract mucosal epithelia, and genitourinary tract mucosal epithelia
How can pathogens cross the epithelial barriers? (3)
1. they may adhere to the surface and infect the cell or cross the epithelial barrier
2. they may also colonize the epithelia
3. an unnatural breach in the epithelial surface may also let them in (ex: cut, wound, burn)
The common portal of entry through the skin occurs through ____ ____ with microbes.
The respiratory tract has ____ and ____ that work together in the upper segment and surfactants in the lungs (lower segment).
mucus and cilia
The upper airway begins at the ____ and ends in the ____ and is protected by the ____ ____.
nose, bronchioles, mucociliary escalator
Mucus secreted by ____ ____ forms a fine layer lining the airway and trapping microorganisms
____ waft the mucus towards the mouth and nose, where trapped organisms are cleared by sneezing or coughing.
Mucus secretion is abnormal in ____ ____ and cilia are defective in ____ ____ ____.
cystic fibrosis, primary ciliary dyskinesia
The main defenses in lower respiratory tract are ____ secreted by ____ ____ ____.
surfactants, type II pneumocytes
Why might organisms trapped in mucus not be able to cause infection?
because they cannot adhere to cell surface
What is the immune function of surfactant?
binds to components of the cell surface of pathogens and causes them to agglutinate. That leads to destruction by phagocytes.
What common practice can disrupt the normal flora in both the GI tract and in the genitourinary tract, making these areas more prone to infection?
What are some features of the genitourinary system to keep microbes out?
1. Defensins and other antimicrobial products produced by epithelial cells and commensals
2. Constant flushing of urinary tract
3. Acidic vaginal pH and commensal bacteria
4. Spermine and zinc in semen are antibacterial (keeps the semen sterile)
5. Lactoperoxidase in milk (keeps milk sterile for the baby)
Are tears a feature of the innate immune system?
yes, because they wash away pathogens and contain antimicrobial substances
What are the 2 types of defensins and where else are they found?
alpha and beta; in neutrophil granules
Defensins have _____-spectrum antibiotic properties and have increased production in response to inflammatory _____.
What are three types of epithelia-associated cells that are also B cells and T cells that are exceptions to the rules?
intraepithelial T lymphocytes (IELs), B-1 cells, mast cells
Intraepithelial T lymphocytes are associated with ____ epithelial cells, express ____ ____ of limited diversity, and recognize ____ structures.
barrier, antigen receptors, shared
Intraepithelial T lymphocytes also secrete ____, activate ____, and kill ____ cells.
cytokines, phagocytes, infected
B-1 cells are located in the ____ cavity and are similar to IELs. They can respond to microbes and toxins that breach the walls of the ____, and they produce natural ____ (IgM).
peritoneal, intestine, antibodies
____ and ____ are circulating phagocytes that are recruited to the site of infection.
monocytes and neutrophils
What are the 7 steps of phagocytosis?
1. chemotaxis and adherence of microbe to phagocyte
2. ingestion of microbe by phagocyte
3. formation of a phagosome
4. fusion of the phagosome with a lysosome to form a phagolysosome
5. digestion of ingested microbe by enzymes
6. formation of residual body containing indigestible material
7. either some of the peptides are held for antigen presentation or discharge of waste materials
NK cells are a subset of ____. They are neither __ cells nor __ cells.
lymphocytes, T cells, B cells
Do NK cells kill immediately? Why or why not?
no, because they don't want to accidentally kill the wrong things.
What are some of the effector functions of NK cells? (7)
1. kill infected cells
2. operate in a similar manner to CTLs
3. have granules
4. eliminates reservoir of infection
5. can kill sooner than CTLs
6. IFNγ secreted by NK cells activates macrophages to destroy microbes/cells (positive feedback loop)
7. controls infection to allow T cell-mediated immunity to develop
What do the granules in NK cells contain and what do they do? (2)
1. contain perforin (creates pore)
2. contain granzyme (induces apoptosis)
The complement cascade is activated directly by ____ and promote ____ and ____ of microbes.
microbes; inflammation and destruction
What are the 3 pathways of complement?
1. classical pathway
2. alternative pathway
3. lectin pathway
The classical pathway is part of ____ immunity and needs ____ so it won't work until it has those.
The ____ pathway directly recognizes microbial structures and is part of innate immunity.
In the ____ pathway, mannose binding lectin (MBL) recognizes mannose residues on microbial glycolipids and glycoproteins.
The lectin pathway leads to activation of the ____ pathway and is part of ____ immunity.
Mammalian cells express ____ proteins that protect uninfected cells. This keeps us from putting holes in our own cells.
Cytokines recruit and activate _____. They also regulate ____ ____.
leukocytes (WBCs); immune response
What are the sources of cytokines in innate immunity?
macrophages, neutrophils, NK cells, endothelial cells, and epithelial cells
Mannose-binding lectin serves as an ____, which makes the microbe a ____ for ____.
opsonin, target, phagocytosis
Mannose-binding lectin (an opsonin) binds to ____ that are unique to microbes. ____ then bind to the attached MBL.
Mannose-binding lectin and C-reactive protein both activate ____ and act as ____.
Because of C-reactive protein, ____ levels increase during the acute stages of many infections.
Innate immunity signals to activate ____ ____ __ and __ ____. This is a ___ signal activation.
antigen specific T and B cells; 2
Innate immunity MUST have two signals to be activated. The first signal is ____ and the second signal is ____ ____ or ____ of ____ ____.
antigen, microbial product or component of innate immunity
The second signal of innate immunity could be a ____, ____, or ____ (on APCs).
complement, cytokines, or costimulators
The ____ signal of innate immunity will activate the response. The ____ of signal dictates the type of response.
The two types of second signal that dictates type of response are:
intracellular microbes and extracellular microbes
With ____ ____ as the second signal, cytokines lead to macrophage activation, leading to destruction of microbes and presentation to T cells, leading to T cell-mediated immunity.
With ____ ____ as the second signal, there is complement activation, which leads to activation of B cells and increased production of antibodies
Innate immunity and adaptive immunity have ____ communication with each other.
bidirectional (this allows innate to stimulate adaptive and adaptive to communicate with the innate as well)
The inflammatory response is an ____ response, where ____ are recruited to the site of infection in order to eliminate the ____.
early, leukocytes, infection
Cytokines (TNF, IL-1, chemokines), microbial products, and coagulation proteins act on ____ cells and ____.
endothelial cells and leukocytes
In the innate response, large numbers of ____ migrate to site, which are then large numbers of ____/____.
neutrophils; monocytes/ macrophages
Inflammation usually causes little damage to ____ tissue, but prolonged inflammation can add to damage caused by ____.
What are some examples of systemic changes in innate response?
1. increased production of leukocytes
3. changes in plasma protein levels
4. shock, DIC, multiple organ failure, and death (these are only in extreme cases)