15 Immunology I (Immune Sys. Overview/Innate Immunity) Flashcards
3 ways the body’s immune sys responds to the presence of microbes? What does each entail?
- Tolerance (do nothing - applies to harmless microbes)
- Segregation (keep microbes away from places they shouldn’t normally be)
- Combat (mount an anti-microbial response if microbes are harmful)
Fns of the human immune system?
- Create physical/biological/chemical barrier that prevents foreign material from entering “internal” (sterile) body sites
- Tell the diff b/w things that’re foreign to the body (“non-self”) and things that are “self” (and eliminate “foreign” stuff)
- Create a “memory” of previously-encountered foreign material > faster, stronger response to re-exposures
T or F: The way the immune system deals with diff types of microbes is the same regardless of the type of pathogen.
F
The immune sys deals w/ diff types of microbes (e.g. viruses, which replicate INSIDE cells) differently than others (e.g. bacteria, which usually replicate OUTSIDE of cells)
Two types of immunity?
- Innate immunity
2. Acquired (adaptive) immunity
What is innate immunity composed of? (2)
- External barrier defenses
2. Internal cellular and biological defenses
What is adaptive immunity composed of? (2)
- Antibody-mediated (humoral) immunity
2. Cell-mediated immunity
This type of immunity responds the SAME WAY regardless of the type of microbe
Innate immunity
This type of immunity has an “individual” response designed for ea. diff microbe.
Adaptive (acquired) immunity
In innate immunity, what’re the external (surface) entry barriers? (4)
- Structural defenses (skin, mucous membranes, etc.)
- Mechanical defenses
- Microbial defenses
- Biochemical defenses
What kind of external barrier does this represent?
The skin is dry, salty envir > limits growth of microbes
Structural defenses
What kind of external barrier does this represent?
Normal microbial flora out-competes pathogenic microbes fro nutrients and for attachment sites on epithelial surfaces
Microbial defenses
What kind of external barrier does this represent?
The “flushing” action of fluids (urine, tears, saliva)
Mechanical defenses
What kind of external barrier does this represent?
Cilitated cells in lungs that move mucus toward mouth
Mechanical defenses
What kind of external barrier does this represent?
Chemicals produced by body harm microorganisms or restrict their growth
Biochemical defenses
What does lysozyme do to microorganisms?
What kind of external barrier does this represent?
Degrades peptidoglycan
Biochemical defenses.
What does lactoferrin do?
What kind of external barrier does this represent?
Binds iron> makes it unavailable as a nutrient for bacteria
Biochemical defenses.
What’re the internal cellular and biological defenses of the innate immune sys (if pathogens overcome surface barriers)? (5)
- Interferon
- Phagocytosis
- Inflammation
- Complement
- Fever
T or F: The internal cellular and biological defenses of the innate immune sys act in isolation.
F
They interact closely w/ e/o
What’s interferon? What does it do?
Small peptides produced by a virus-infected cell > It tells other cells to make anti-viral proteins
T or F: Interferons are host-specific (i.e. the human interferon is not the same as that of other mammals)
T
T or F: Interferon is highly specific for certain types of viruses.
F
They’re virus NON-SPECIFIC
How many interferons do humans make? What are they? What do ea. do?
3
INF alpha, beta, and gama
Alpha: stimulate antiviral activity
Beta: Stimulate antiviral activity
Gamma: Stimulates phagocytic cells and helps regulate the acquired/adaptive immune sys
Types of phagocytes in the body?
- Monocytes
- Neutrophils
- Eosinophils
- Macrophages
- Dendritic cells
What is phagocytosis?
When a phagocyte digests and eliminates dead tissues AND any foreign material
What types of cells are phagocytes?
WBCs
What can increases in WBC numbers, neutrophils, and bands mean?
Bacterial infection is present
What can decreases in total WBC numbers and increases in lymphocytes mean (sometimes)?
A viral infection is present (for some viruses, at least)
List the steps of the mechanism of phagocytosis? (5)
- Bacterium becomes attached to membrane evagination (“pseudopodia”)
- Bacterium gets ingested > forms phagosome
- Phagosome fuses w/ lysosome
- Lysosomal enzymes digest captured material
- Digestion products are released from cell
T or F: Phagocytosis is v. specific for particular microbes.
F
Phagocytosis is NON-SPECIFIC
There’s no such thing as a diff phagocytic cell for every diff species of bacteria
How does a phagocyte recognize a foreign microbe and not one of your own cells?
Cell surface molecules on the phagocytic cells that’re designed to recognize characteristic molecules found in microbes but NOT in host cells (“Pattern recognition receptors”)
e.g. peptidoglycan, LPS, chitin in fungal cell walls, etc.)
How are bacteria killed once ingested by a phagocyte?
Degradative enzymes and other toxic molecules found in the lysosome of the phagocyte
What happens to the stuff phagocytes spit out?
They’re adsorbed and further degraded
What negative thing can occur with the degraded microbes once they’re released from phagocytes?
They can irritate surrounding tissues if there’s a lot of it
How can bacteria defend themselves against phagocytosis? (3)
- They produce capsular polysaccharides (hard for phagocytes to grab on to them)
- They secrete “toxins” that target and destroy phagocytes
- They survive after being ingested by escaping phagosome-lysosome compartment
Other than phagocytosis, what’re other ways the innate immune sys can kill microbes? How does each work?
- Extracellular killing by eosinophils (Secrete toxic proteins that perforate parasite wall
- Extracellular killing by natural killer (NK) cells (recognize a virus-infected cell and destroy it by secreting degradative enzymes)
How could the innate immune sys kill s.th that’s bigger than phagocytes (e.g. parasites)?
Use eosinophils
How could the innate immune sys kill viruses that’re hiding in your own cells?
Use NK cells
What is inflammation?
A rapid biological response to TISSUE DAMAGE
What can damage tissue?
- Physical agents (e.g. cuts, burns, bites)
2. Microbial agents that cause disease
Five main signs of inflammation?
- Pain
- Redness (erythema(
- Immobility (loss of fn)
- Swelling (edema)
- Heat
(PRISH)
What’s the purpose of inflammation?
- Attract phagocytes + other immune cells to site of infection
- To repair and heal injured tissues (which can occur once it’s been cleaned up of pathogens by phagocytes)
T or F: Inflammation is a harmful process.
F
Inflammation is a correct and appropriate response to damaged tissues or to the presence of microbes
Name two chemicals that’re released during inflammation. What does ea. do?
- Histamine (vasodilation, increased blood vessel permeability, nerve ending stimulation - pain)
- Prostaglandin (vasodilation, fever, pain)
What kinds of drugs can be used to minimize inflammation? (3)
- Anti-histamines
- Aspirin or ibuprofen
- Corticosteroids
Two types of inflammation?
- Acute
2. Chronic
This type of inflammation is an immediate and beneficial response to tissue injury or microbes
Acute inflammation
This type of inflammation is a delayed and potentially harmful response that occurs if the microbe or tissue injury persists
Chronic inflammation
Which type of inflammation is useful and beneficial?
Acute inflammation
Which type of inflammation is harmful?
Chronic inflammation
Which type of inflammation take a long time to resolve?
Chronic inflammation
Which type of inflammation has no long-term consequences?
Acute inflammation
What can chronic inflammation result in?
Tissue damage and scarring due to continuous phagocytic cell activity in the affected area
What is complement? Why the name, “complement”?
A family of ~30 diff proteins found in the blood serum.
They’re named “complement” bc they work along w/ antibodies
Three main fns of complement proteins?
- Make phagocytosis more efficient via “opsonization”
- Destroy bacteria by forming “Membrane Attack Complexes”
- Help to induce and/or regulate other immune responses
How can complement proteins regulate other immune responses?
- promote vasodilation, stimulate inflammation
2. help remove antibody + antigen complexes from circulation
Ppl w/ genetic defects that result in the loss of one or more complement proteins are susceptible to what?
Microbial infections and other “immunologic” diseases
What is “fever”?
A biological response to “pyrogenic” (fever-inducing) agents
Name two “external” pyrogens
- bacterial LPS
2. fungal wall components
Give an e.g. of an “internal” pyrogen
Chemicals released from phagocytes
What is the MOA of pyrogens
- Pyrogens trigger increase of prostaglandin production in the hypothalamus
- Elevation of hypothalamic thermoregulation (i.e. the body’s “thermostat” is set to a higher temp)
If a drug or other injectable product is labeled “non-pyrogenic”, what does this mean?
All chemicals that are capable of producing a fever have been removed
Name four benefits of a fever?
- Inhibits growth of temp-sensitive microbes
- Reduces availability of nutrients req’d by microbes for growth
- Increases metabolic activity of phagocytic cells
- Stimulates acute inflammation, interferon production, etc.
T or F: Low-grade fever is more dangerous than high grade fever.
F
High-grade fever is more dangerous (>40ºC)
Best way to reduce a fever?
Use agents that bock prostaglandin synthesis
Type of immunity that lacks memory and is non-specific?
Innate immune sys
What’re the first two (out of three) lines of defense against pathogens?
1st line: Surface entry barriers
2nd line: Internal (chemical/cellular) barriers
What’s the third line of defense against pathogens?
The acquired immune system
T or F: The second exposure to the same microbe is eliminated faster by the innate immune sys
F
