Exam II Review Flashcards
Describe innate and adaptive immunity in terms of their specificity
Innate is general, first and second lines of defense, recognizes things like peptidoglycan or flagella (general pathogenic characteristics)
Adaptive is specific, utilizes humoral (antibodies, B cells), and cell-mediated responses (T cells, helper and cytotoxic)
Skin is one of the first lines of defense for innate immunity, why can’t most pathogens penetrate the skin?
Dry, acidic, and salty
What do mucous membranes contain that works as the first line of defense for innate immunity, and how does it work?
Lysozyme: works by cleaving between NAG and NAM of peptidoglycan
Lactoferrin: iron scavenging (pathogens contain siderophores)
Lactoperoxidase and pH modification also possible
What is the second line of defense for the innate immune system?
Interferons [alpha, beta, and gamma]
Which interferon is responsible for enhanced phagocytic activity? (acts on bacteria)
IF-gamma
Which interferon is responsible for affecting neighboring cells and responds to viral infection?
IF-alpha and IF-beta
What are the innate immune defenses of the respiratory system?
mucous and ciliated cells in the nose and pharynx work to move things toward the throat to be coughed out
lower respiratory tract protected by alveolar macrophages and mucociliary escalator
What are the innate immune defenses of the eyes?
Lacrimal apparatus: produces tears containing lysozyme that can drain out the nose
also eyelashes, blinking
What is the function of eosinophils?
Protect us from large parasitic infections like helminths and roundworms using granzymes and perforin
What type of cells may act as phagocytic cells?
macrophages, dendritic cells, neutrophils
How do the chemical mediators of inflammation function?
prostaglandins release histamine and bradykinins which cause vasodilation and increased capillary permeability, resulting in edema/swelling
How does fever enhance our innate immune response?
By increasing metabolism and transferrins
Who secretes transferrins (host or pathogen) and what do they do?
Host secretes transferrins which prevents free iron from being taken up by pathogens with siderophores
When is fever detrimental? What cells are most sensitive?
If body temp goes too high; neurons/brain cells are the most sensitive to body temperature
What are the important chemical mediators of fever?
Activation of pituitary gland causing release of prostaglandins; interleukin-1 leads to T cell activation
Where do the 3 complement pathways converge?
C3
What are the 3 main activities of the complement?
- Formation of the membrane attack complex (MAC) which is dependent on C5 activation, leading to C6-9
- Opsonization - attraction of phagocytic cells
- Enhances inflammation
What are PAMPs and name examples
Pathogen Associated Molecular Patterns
LPS, Peptidoglycan, Flagella
What are TLRs and how do they work
Toll-like receptors; act as ligand-gated receptors that recognize PAMPs; can be located anywhere in/on the cell
*She gave the example of an inflammation response to TLR binding a PAMP
What is the difference between a TCR and a TLR?
TCR = T cell receptors; located on helper T cells and cytotoxic T cells ONLY
TLR = Toll-like receptor; found on all cells
Which will generate stronger response: T-independent B cell activation, or T-dependent B cell activation?
T-dependent B cell activation, which requires helper T cells. T helper cells require two signals in order to recognize a particular pathogen
Do helper T cells bind to free antigens?
NO
They only bind to antigens coupled with MHC class II molecule (on APC)
Where are MHC class I molecules found? What occurs if they are missing? What about when antigen is bound?
all nucleated cells; if they are missing, natural killer cells are activated. When antigen is bound they will activate cytotoxic T cells
True or false: there is only one pathway through which cytotoxic T cells can initiate cell death
False!
Cytotoxic T cells or Natural Killer cells can cause apoptosis, cell death, or necrosis
*Apoptosis is preferred response
What are the 3 types of APCs that exhibit MHC class II?
B cells, dendritic cells, and activated macrophages
What type of antigen is capable of linking MHC class II and T cells together, causing activation of T cell in the absence of a specific antigen?
Superantigen
There are 2 signals necessary to T cell activation, the first signal involves co-receptors. What are co-receptors?
CD4+ = helper T cells
CD8+ = cytotoxic T cells
Which type of T cell requires MHC class I presenting an antigen to the T cell receptor?
Cytotoxic T cell with co-receptor CD8+
this will lead to one of several pathways toward cell death
what type of cells produce antibodies?
plasma cells
What is the structure of an antibody?
Made up of light chains and heavy chains with two domains: variable region and constant region
Which region of an antibody binds to the antigen? Which region binds to the surface of the antibody?
Variable region binds to the antigen, constant region binds to the antibody itself
Where would you find an antibody such as IgM, IgG, IgA, IgD, or IgE?
In the blood!
Which antibody is the first to be produced in response to an infection? Second? What is the process called when the antibody present changes?
First is IgM - agglutination, Second is IgG
Class switching occurs between IgM and IgG
Describe the concept of combinatorial joining
Random deletion events in which variable exons are spliced together with constant region. The constant region dictates the class of antibody prior to forming final mRNA strand. Overall purpose is to create diversity of antibodies
What areas of the body should be free of microbes?
Lower respiratory tract, kidneys and beyond (bladder), blood, CSF
Where would you find the most normal flora?
intestines
What is a reservoir for Shigella?
water
*Reservoirs can be inanimate or animate!
Define vector
organism that spreads pathogen from one host to another; for example: arthropods (fleas, ticks, lice)
Fomite
inanimate object that can be contaminated with a pathogen
What are the stages of disease in order?
incubation period, prodromal stage, period of illness (may plateau or continue - chronic, convalescence
What is the portal of entry for an opportunistic pathogen invading a surgical site or abscess?
Parentaral route
Name 5 virulence factors that contribute to adherence
Fimbriae, pili, M proteins, capsules, and biofilms
Describe catalase
reactive oxygen species that are converted into water and gas; upregulation of catalase occurs in the phagolysosome
Describe coagulase
Converts fibrinogen into fibrin, forming wall around pathogen so phagocytic cells cannot get to it
What do proteases and kinases do?
proteases cleave immunoglobulins, kinases break down fibrin clots
Which pathogen is known to exhibit antigenic variation?
Neisseria with its varying pilum proteins
Which pathogens exhibit intracellular growth?
Chlamydia, Rickettsia, Shigella, Listeria
Which pathogen utilizes host cell actin?
Shigella
Name some exotoxins from organisms discussed in class
Botulinum toxin, Shigatoxin, Cholera toxin, Pertussis toxin, Superantigens, Enterotoxin
What does the pertussis toxin do?
causes mucous production, then cytotoxin kills ciliated cells which leads to paroxysmal cough
Lysogenic conversion occurs when phage infection brings in virulence factors. Name 2 organisms that exhibit lysogeny
S. pyogenes (strep throat) can lead to scarlet fever, rheumatic fever, cholera. Staphylococcal enterotoxin also.
What is the function of an Opa protein?
prevents T cell proliferation
Define bacteremia, toxemia, and viremia
Bacteria in the blood
Toxins in the blood
Viruses in the blood
What is the difference between infection and intoxication?
infection occurs when colonization by an organism results in disease
intoxication occurs due to the presence of a toxin (toxemia)
Compare botulism and tetanus toxins
Both have AB toxins, both are neurotoxins, both produced by clostridium species, both act on neuromuscular junction of synapses
Describe Botulism
flaccid paralysis due to blocked release of ACh
Describe Tetanus
rigid paralysis due to inhibited release of GABA and glycine
Toxins are named by activity. Describe an AB toxin
AB toxins have Active region and Binding region
What is an obligate intracellular parasite that has an RB and an EB?
Chlamydia
Why is Shigella unique for an enteric?
It lacks a flagellar antigen so it is non-motile; other enterics have flagella
What are K, H, and O antigens?
O is LPS on surface
H is flagella
K is capsule
What are 5 modes of transmission
airborne contact vehicle vector-borne vertical ---- example: Listeriosis!!
In what type of tests might fluorescence be used?
microscopy, cell sorting, flow cytometry
