Practice Questions Flashcards
_________enzyme is present ONLY in phagocytic cells of the immune system (mostly neutrophils) and converts _________ to _______.
- _________enzyme is present ONLY in phagocytic cells of the immune system (mostly neutrophils) and converts _________ to _______.
a. Myeloperoxidase (MPO) MPO contains 2 Fe heme-like centers=green=pus
b. H202 —> HOCl (Hypochlorous Acid: powerful toxin that destroys bacteria through halogenation and oxidation reactions)
_________ allow cells to upregulate production of free radicals in response to infection (which causes damage to lipids, proteins, carbs, and DNA»_space;> collateral damage: cell death/CA/disease.)
_________ allow cells to upregulate production of free radicals in response to infection (which causes damage to lipids, proteins, carbs, and DNA»_space;> collateral damage: cell death/CA/disease.)
Respiratory Bursts
Three year old kiddo is brought into your office today with his third bout of pneumonia since January (you culture his sputum and later find the culprit to be aspergillus). Upon further examination, you also find oral thrush, which you treated him for three weeks ago when it developed after antibiotic treatment for his pneumonia. You suspect a rare X-linked disease: Chronic Granulomatous Disease, may be underlying these weird recurrent infections. As a result you are more worried about him getting infected by staph aureus or nocardia than you are about a streptococcus infection. Why?
a. CGD is a deficiency of NADPH oxidase in phagocytes. Aspergillus, staph aureus and nocardia are catalase negative organisms = they degrade enough H202 into ROS that the human’s phagocytes can use those ROS against the bacteria in absence of the phagocytes’ own NADPH oxidase products.
b. Catalase Positive bacteria (eg streptococcus) degrade a minimal amount of H202, so human phagocytes without NADPH oxidase don’t have enough ammunition to destroy the bacteria.
A lumberjack was injured near Cloquet [nice :)] when an enormous tree fell in an unsuspected fashion, pinning his right leg to the ground. The circulation in his leg is compromised. Since his leg isn’t broken, and he isn’t bleeding (besides a few scrapes), the lumberjack thinks that once his leg is unpinned, he will be “out of the woods.” But what is he at risk for?
a. Reperfusion Injury.
blocked blood flow —>decreased oxygen to tissues —> decreased ATP available —-> increased Na+ and Ca++
The reduced state of the electron carriers in the absence of oxygen PLUS the loss of mitochondrial ion gradients/membrane integrity leads to HUGE increase in Superoxide production when Oxygen becomes available again during reperfusion.
- So, you’re a Paneth Cell. Awesome. Tell me i) where are you located?; ii) what feature of the innate immune system do you wear like a badge of honor?; iii) what does this feature allow you to do?
a. i) In the small intestine; ii) you totally rock an ALPHA-Defensin known as Human Defensin (HD); This DEFENSIN enables you to increase cellular permeability and modulate the inflammatory response
i. Note: even though it’s categorized as an “alpha”-defensin, the other kids at school can’t make fun of you cause it’s still a BETA-pleated sheet, just like all the other Defensins, but yours is named “alpha” because the linking pattern of your cysteines is just a little different. You’re unique. And that makes you special.
2. TLRs are activated by the following factor derived from fragments of the host: . PAMP a. DAMP b. CHAMP c. LAMP
. Answer: DAMP
3. Which TLR is the only one to NOT utilize the MyD88 cascade pathway? . TLR5 a. TLR9 b. TLR3 c. TLR1/6
. Answer: TLR3
- With respect to the various TLR cascade pathways, those that feature IRF3 yield expression of __a__, those with IRF7 yield expression of __b__, while the “mother of all immune system transcription factors” known as __c__ yields expression of __d__.
a IFN-Beta
b. IFN-Alpha
c. NF-kB
d. pro-inflammatory cytokines
- __a__ are the most important players in the acute inflammatory response, while __b__ govern chronic inflammation. Regarding the allergic response, __c__ are involved in the immediate phase of an allergic reaction, whereas __d,e__ are involved in the late phase.
a. PMNs (Neutrophils)
b. Macrophages
c. Mast Cells
d. Eosinophils
e. Basophils
- During myelopoeisis, a Monocyte can be differentiated into a(n) _____ if exposed to _____.
. TWO possible answers:
. Macrophage; M-CSF + GM-CSF
i. Dendritic Cell; GM-CSF + IL-4
- What are the THREE cells capable of antigen presentation (APCs)?
. Dendritic Cells, Macrophages, B Cells
- You are on clinical rounds when you meet an 18 month old female brought in by her mother. The child was recently diagnosed with MHC Class II deficiency. What type of cells do you expect to see depleted in the child? This is the result of the inability of what type of selection?
a. The child would be deficient in CD4+ cells as a result of the lack of positive selection occuring in the thymus due secondary to MHC class II deficiency. If the thymus is deficient in MHC Class II, the maturation of CD4 T cells will not occur. CD8 T cells will be unaffected as they bind to MHC class 1 molecules.
- The child was not diagnosed with MHC Class II deficiency until 6 months of age when she presented with opportunistic pneumonia. Why was the child’s health protected, despite having the autosomal recessive MHC Class II deficiency, until 6 months of age?
. The child was protected via receiving IgG from her mother through passive immunity. Passive immunity typically only lasts 6 months before the mothers IgG starts to deplete from the child’s system, and thus 6 months is the age where many hereditary immunological deficiencies first present.
- Why is the type of immunity described in number 2 “faster”?
. IgG is directly passed to the child through passive immunity. Via active immunity, IgM is the first antibody to appear as it is better at complement activation in response to new antigenic exposure. IgG is generally not made for a week or two in active immunity.
- The mother is also worried about her daughter having symptoms of asthma. What is causing her daughter’s bronchoconstriction? What hypersensitivity type is this?
. This is a type 1 hypersensitivity reaction known for its fast onset in response to environmental trigger. It’s caused by IgE attaching to mast cells, and when this pairing binds to antigen, degranulation occurs, resulting in the release of histamine from mast cells in addition to leukotrienes and prostaglandins-> bronchoconstriction.
- You are a scientist at the NIH studying a rare disease caused by a mutation in the J-chain. (This is in the antibody structure, we are not talking about the J region of DNA that goes through VDJ recombination). What Ig isotypes will this mutation affect? And subsequently what parts of immune function will lose effectiveness?
a. Isotypes IgM and IgA will be affected because they use the J-chain in their structure to hold things together
i. IgM is the first Immunoglobulin to appear in serum at the onset of infection or after a vaccine. Good sign of current infection
ii. IgA has a strong protective role in secretions on mucous membranes
- What is the valence of IgM? What would be the valence of IgM if you were able to remove all the the light chains and not disrupt anything else?
a. Valence = number of antigenic determinents (AKA epitopes) that an antibody can theoretically bind
i. IgM is composed of 5 basic units with 2 binding regions each. This gives it a valence of 10
ii. Remember that in order to bind to an epitope the antibody must have a V region from BOTH the light and heavy chains to make the combining site. Without the light chains as part of the combining sites, this molecule will bind to no antigens and have a valence of 0.
- There are 10 isotypes of immunoglobulins: 4 IgG, 2 IgA, 2 IgM, 1 IgD, and 1 IgE. These are based on slight difference in amino acid sequences of their heavy (H) chain constant (C) regions. Immunoglobulins can be further differentiated into allotypes and idiotypes. What determines allotypes and idiotypes?
. Allotypes - Inherited minor allelic differences in the Ig sequences
. possible genetic determinant in immune function
a. Idiotype - Differences in individual combining sites (the combined light and heavy chain variable regions) also known as the complementarity-determining region (CDR).
