L2300: PQs for Final Exam
What is the role of lactoferrin?
It binds iron, removing it as an element source that would otherwise support microbial growth.
How could colony-stimulating factors be used as a therapy?
It can be used to direct the accumulation of a given cell type.
How is an epitope different from an antigen?
An epitope is a very small part of an antigen; B and T cell receptors bind to epitopes on antigens.
Which one of the following is a recommended therapy for HSV genital infection? A. Acyclovir B. Gardasil-9 C. Herpes immune globulin D. Ribavirin E. Interferon alpha F. Attenuated live virus vaccine
A. Acyclovir
Tuberculosis is characterized by granulomas called tubercles. What is a granuloma?
A concentrated group of macrophages, giant cells, and T cells that surrounds microbes or material that cannot be destroyed
How does a naive lymphocyte differ from an activated one?
A naive lymphocyte has never "seen" the epitope to which it is programmed to respond. Activated lymphocytes have encountered the epitope and have received any required accessory signals.
How does fever inhibit the growth of pathogens?
A temperature above a microbe's optimum growth temperature can cause the growth rate to decline sharply.
Ag-Ab binding may result in _______________________. Check all that apply. A. Agglutination B. Activation of the classical complement pathway C. Prevention of adherence D. Neutralization E. Opsonization
A. Agglutination B. Activation of the classical complement pathway C. Prevention of adherence D. Neutralization E. Opsonization
Loss of which of the following virulence factors through mutation would be most likely to reduce the ability of pneumococcus to cause meningitis? A. Capsule B. Flagella C. Lipopolysaccharide D. Lipase E. Streptolysin O (hemolysin)
A. Capsule
Which of the following is NOT generated during anaerobic metabolism of glucose? A. Citrate B. Pyruvate C. Glyceraldehyde-3-phosphate D. Glucose-6-phosphate E. Acetyl CoA
A. Citrate
Several 12 YO males at a sleepaway summer camp develop conjunctivitis, pharyngitis, and an upper respiratory tract infection. They have a mild fever but no rash. The public health department isolated a virus from the swimming pool. What describes the most likely causative agent? A. Detergent-insensitive virus that replicates in the nucleus B. Detergent-sensitive virus that replicates in the cytoplasm with noninfectious genome C. Detergent-sensitive virus that replicates in the cytoplasm with infectious genome D. Detergent-insensitive virus that replicates in the cytoplasm E. Detergent-sensitive virus that replicates in the nucleus
A. Detergent-insensitive virus that replicates in the nucleus
A 56 YO male complains of severe pain caused by a belt of vesicular lesions across the left side of his abdomen. What is the source of his infection? A. Endogenous reactivation of an earlier infection B. Aerosolized droplets of the causative agent C. Contaminated food or water D. Punture with a contaminated object E. Sexual activity
A. Endogoenous reactivation of an earlier infection
Laboratory diagnosis of vaginal trichomoniasis is commonly made by which of the following methods? A. Finding feeding, motile, vegetative forms in a saline wet mount of vaginal discharge. B. Identifying cysts in an iodine stained preparation of vaginal secretion C. Testing for specific antibodies against T. vaginalis in the patient's serum D. Using an acid-fast stain to highlight the parasite E. Staining a thin blood smear with common blood stains (H&E or Giemsa).
A. Finding feeding, motile, vegetative forms in a saline wet mount of vaginal discharge
Identify the CORRECT statement(s) regarding HIV. Check all that apply. A. HIV reverse transcriptase changes viral RNA into DNA. B. HIV requires both CD4 and a chemokine coreceptor to enter cells. C. The Western blot test is the initial diagnostic test. D. HIV adversely affects B cells and plasma cells. E. Both CD4+ T cells and macrophages can be infected
A. HIV reverse transcriptase changes viral RNA into DNA. B. HIV requires both CD4 and a chemokine coreceptor to enter cells. E. Both CD4+ T cells and macrophages can be infected
A mother and newborn are exposed to a pathogen while at the hospital for a routine checkup and breastfeeding clinic. This same pathogen had infected the mother about a year previously, and she successfully recovered from the subsequent illness. Immunity may be innate or acquired. Which of the following best describes acquired immunity with respect to the newborn? A. Maternal transfer of sIgA B. Inflammatory response C. Complement cascade D. IgM in the colostrum of breast milk E. Presence of NK cells
A. Maternal transfer of sIgA
A 43 YO anatomy professor is working in her garden, pruning rose bushes without gloves. A thorn enters the skin of her forefinger. The area later becomes infected and she removes the thorn, but there is still pus remaining at the wound site. Which of the following cells functions in the formation of pus? A. Neutrophils B. Lymphocyte C. Eosinophil D. Basophil E. Monocyte F. Megakaryocyte
A. Neutrophils
Which of the following is a widely used nontreponemal serologic test? A. RPR B. Dark field microscopy C. MHA-TP D. FTA-ABS E. TP-PA
A. RPR
Formation of biofilms attached to fibronectin and fibrinogen coating plastic devices like catheters and heart valves is a virulence mechanism of _____________________. A. Staphylococcus B. Streptococcus C. Pseudomonas D. Clostridium E. Bacillus
A. Staphylococcus
Which cell type would NOT be present in a boy born without a thymus? A. T cell B. Macrophages C. NK cell D. B cell E. Neutrophils
A. T cell
Select the incorrect statement(s) regarding viruses. Check all that apply. A. The receptors to which animal virus attachment proteins usually bind are carbohydrates. B. The structure of plant, animal and bacterial viruses are each, fundamentally, verry different from one another. C. Viroids characteristically are composed of dsRNA. D. Carriers may have a persistent infection E. Naked and enveloped viruses both may enter the host via endocytosis.
A. The receptors to which animal virus attachment proteins usually bind are carbohydrates. B. The structure of plant, animal and bacterial viruses are each, fundamentally, verry different from one another. C. Viroids characteristically are composed of dsRNA.
Identify the CORRECT statement(s) regarding yeasts. Check all that apply. A. They are the pathogenic form of dimorphic fungi usually seen in tissues. B. Yeasts have eukaryotic nuclei and contain chloroplasts in their cytoplasm. C. Yeasts produce exotoxins. D. Yeasts have cholesterol in their cell membranes. E. Yeasts have chitin in their cell walls.
A. They are the pathogenic form of dimorphic fungi usually seen in tissues. B. Yeasts have eukaryotic nuclei and contain chloroplasts in their cytoplasm. C. Yeasts produce exotoxins. D. Yeasts have cholesterol in their cell membranes. E. Yeasts have chitin in their cell walls.
The genome of retroviruses consists of: A. Two copies of ssRNA plus copies of RT, PR, IN, and tRNAs B. Segmented ssRNA plus tRNA and RT. C. Segmented ssDNA plus an integrase, protease, reverse transcriptase and transfer RNA D. Two copies of dsRNA and DNA polymerase E. Two copies of ssDNA plus 3 enzymes
A. Two copies of ssRNA plus copies of RT, PR, IN, and tRNAs
The most common way travelers contract leptospirosis is from ____________________. A. White-water rafting B. Contact with farm animals C. Black-water rafting D. Hotel swimming pools E. Ingesting leptospiral-contaminated foods
A. White-water rafting
Each of the following statements about HIV is correct EXCEPT: A. A DNA copy of the HIV genome integrates into host cell DNA. B. Acyclovir inhibits HIV replication C. HIV is an enveloped RNA virus D. The virion contains an RNA-dependent DNA polymerase
B. Acyclovir inhibits HIV replication
A 63 YO HM develops fever within 2 days of surgery for a hip replacement. Treatment with ampicillin does not eliminate the infection. Gram-positive, coagulase-positive cocci were isolated from the blood. Which of the following is the most probable reason for antibiotic failure? A. Inactivation by coagulase B. Antibiotic-resistant target enzyme C. Mutation in porins prevents drug entry D. Chromosomal mutation in ribosome prevents drug action
B. Antibiotic-resistant target enzyme
Short incubation food poisoning, caused by the ingestion of preformed enterotoxin, is caused by which bacteria listed below? Check all that apply A. Enterococcus faecalis B. Bacillus cereus C. Staphylococcus epidermidis D. Streptococcus pneumoniae E. Clostridium perfrigens F. Staphylococcus aureus G. Streptococcus pyogenes
B. Bacillus cereus E. Clostridium perfringens F. Staphylococcus aureus
Each of the following organisms is an important cause of urinary tract infections (UTIs) EXCEPT: A. Proteus mirabilis B. Bacteroides fragilis C. Klebsiella pneumoniae D. Escherichia coli E. Staphylococcus saprophyticus
B. Bacteroides fragilis
Select the CORRECT statement(s) regarding host-microbe interactions. Check all that apply. A. The infectious dose of most pathogens is about equal B. During incubation and convalescence a person may still spread infectious organisms C. Obligate intracellular parasites may be grown in special synthetic media D. Protein A is a surface constituent of S. aureus as well as a secreted product and binds to the Fc portion of immunoglobulins E. The M protein of group A streptococci is the anti-phagocytic component of the fimbriae.
B. During incubation and convalescence a person may still spread infectious organisms D. Protein A is a surface constituent of S. aurues as well as a secreted product and binds to the Fc portion of immunoglobulins E. The M protein of group A streptococci is the anti-phagocytic component of the fimbriae.
During the course of a patient's HIV infection, the target cell changes from macrophages and some CD4 T cells to include other CD4 T cells. A mutation in which viral protein would most likely account for this change? A. Protease B. GP120 C. RNA-dependent DNA polymerase D. GP41 E. Reverse transcriptase F. Integrase
B. GP120
Premalignant cells are seen in a Pap smear from a 40 YO HF. Which agent is most likely to be present in these cells? A. HSV type 2 B. HPV type 16 C. Parvovirus B19 D. Adenovirus type 2 E. Chlamydia trachomatis
B. HPV type 16
The identification of bacteria by serologic tests is based on the presence of specific antigens. Which one of the following bacterial components is LEAST likely to contain useful antigens? A. Cell wall B. Ribosomes C. Outer membrane D. Capsule E. Flagella
B. Ribosomes
Which genus is best described as catalse-negative, gram-positive cocci that are aerotolerant anaerobes and form chains? A. Gonococcus B. Streptococcus C. Micrococcus D. Enterococcus E. Staphylococcus F. Stomatococcus
B. Streptococcus
Each of the following statements concerning gonorrhea is correct EXCEPT: A. Infection in men is more frequently symptomatic than in women. B. The definitive diagnosis can be made by detecting antibodies to Neisseria gonorrhoeae in the patient's serum. C. A presumptive diagnosis can be made by finding gram-negative kidney bean shaped diplococci within neutrophils in a urethral discharge. D. Anorectal and pharyngeal infections are important sources of the organism. E. Gonococcal conjunctivitis of the newborn rarely occurs in the US because silver nitrate or erythromycin is commonly used as prophylaxis.
B. The definitive diagnosis can be made by detecting antibodies to Neisseria gonorrhoeae in the patient's serum.
Each of the following statements concerning Candida albicans is correct EXCEPT: A. Candida albicans forms pseudohyphae when it invades tissue. B. The yeast form predominates if cultured in an incubator at 25^C. C. Candida albicans causes diaper rash. D. Impaired cell-mediated immunity is an important predisposing factor to disease. E. The yeast form stains Gram-positive
B. The yeast form predominates if cultured in an incubator at 25^C.
Which one of the following antibiotics is the most appropriate to treat a sever necrotizing skin infection caused by an MRSA strain of Staph aureus? A. Gentamicin B. Vancomycin C. Amoxicillin D. Ciprofloxacin E. Ceftriaxone
B. Vancomycin
Otitis media probably develops from an infection that spreads: A. from the sensory neurons of the middle ear B. upwards through the Eustachian tube to the middle ear. C. from the outer ear to the middle ear D. Through the tympanic membrane E. from the nasolacrimal duct to the middle ear
B. upwards through the Eustachian tube to the middle ear
Why would the discovery of TLRs alter the view that innate immunity is non-specific?
Because they allow cells to detect patterns associated with microbes, indicating that the responses involve some specificity (although not the molecular specificity that characterizes the adaptive responses).
Why can bone marrow transplants be used to replace defective lymphocytes?
Bone marrow has hematopoietic stem cells; in the procedure for a bone marrow transplant, the lymphocytes are destroyed and then another person's bone marrow (containing hematopoietic stem cells) is transferred. The transferred stem cells can develop into new lymphocytes (as well as other blood cells).
Describe two general events that can initiate inflammation.
Invasion by microorganisms and tissue damage
What is the gram-negative bacillus that resembles a plump coccobacilli that tends to resist alcohol decolorization and may be mistaken for Neisseria? A. Salmonella B. Vibrio C. Acinetobacter D. Pseudomonas E. Haemophilus
C. Acinetobacter
A thermal burn patient has an infected area with odiferous, blue-green pus. What is the most likely etiology? A. Streptococcus pyogenes B. Clostridium difficile C. An aerobic gram-negative oxidase-positive rod with polar flagella. D. A facultative anaerobic gram-positive catalase-positive coagulase-positive coccus found in clusters. E. A gram-negative facultative anaerobic rod that lacks cytochrome oxidase and ferments lactose. F. Clostridium perfringens
C. An aerobic gram-negative oxidase-positive rod with polar flagella
A 63 YO man develops fever within 2 days of surgery for a hip replacement. Treatment with ampicillin does not eliminate the infection. Gram-positive, coagulase-positive cocci were isolated from the blood. Which of the following is the most probable reason for antibiotic failure? A. Insufficient dosing schedule B. Inactivation by coagulase C. Antibiotic-resistant target enzyme D. Mutation in porins prevents drug entry E. Chromosomal mutation in ribosome prevents drug action
C. Antibiotic-resistant target enzyme
How can a B cell be distinguished from a T cell? A. T cells mature in the bone marrow B. Extensive gene recombinations occur in B cells C. B cells have surface immunoglobulin D. B cells have a large nucleus-to-cytoplasm ratio E. B cells have a sheep RBC receptor
C. B cell shave surface immunoglobulin
A 67 YO patient with an indwelling catheter develops a fever. Gram-positive coccie are isolated from both his blood and from a biofilm on the catheter. Which of the following traits identify these bacteria? A. Resistance to methicillin B. Growth in bile C. Catalase D. beta-hemolysis E. Spore formation
C. Catalase
Catalase-positive, gram-positive bacilli that are not acid-fast, do not branch, and do not form spores belong to which group of bacteria? A. Streptobacillus B. Actinomyces C. Corynebacterium D. Nocardia E. Clostridium F. Bacillus G. Mycobacterium
C. Corynebacterium
A 25 YO WF is seen on an emergency basis while in shock with generalized flushing of the skin and mucous membranes. A vaginal tampon is present. Toxic shock syndrome is suspected. Which of the the following mechanisms is responsible for toxic shock syndrome? A. Inhibition of acetylcholine release B. Stimulation of G protein C. Cross-linking of MHC-II and TCR proteins D. Activation of adenylate cyclase E. ADP ribosylation of ribosomal protein
C. Cross-linking of MHC-II and TCR proteins
The MAIN host defense against bacterial exotoxins is: A. Helper T cells B. Activated macrophages secreting protesases C. IgG and IgM antibodies D. Neutrophils E. Modulation of host cell receptors in response to the toxin
C. IgG and IgM antibodies
Which of the following is a phagocytic cell found in the human body? a. T lymphocyte B. Mast cell C. Neutrophil D. Erythrocyte E. B lymphocyte
C. Neutrophil
Which one of the following leukocytes is considered a "granulocyte"? A. NK cell B. Macrophage C. Neutrophil D. Plasma cell E. Dendritic cell
C. Neutrophil
Which of the following would be the most appropriate treatment if the diagnosis of a patient is determined to be protozoan vaginitis? Check all that apply. A. Ceftriaxone B. Doxycycline C. Nitroimidazole D. Tinidazole E. Azithromycin F. Metronidazole
C. Nitroimidazole D. Tinidazole F. Metronidazole
Production of exotoxin A, which kills host cells by inhibity protein synthesis, and production of several proteolytic enzymes and hemolysins that destroy cells andd tissue are factors that contribute to pathogenicity of which of the following? A. Burkholderia pseudomallei B. Clostridium difficile C. Pseudomonas aeruginosa D. Vibrio cholerae E. Acinetobacter baumannii
C. Pseudomonas aeruginosa
Select the INCORRECT statement(s) regarding host-microbe interaction. Check all that apply. A. Protein A is a surface constituent of S. aureus as well as a secreted product and binds to the Fc portion of immunoglobulins B. During incubation and convalescence a person may still spread infectious organisms C. The infectious dose of most pathogens is about equal D. Obligate intracellular parasites may be grown in special synthetic media E. The M Protein of GAS is the anti-phagocytic component of the fimbriae
C. The infectious dose of most pathogens is about equal D. Obligate intracellular parasites may be grown in special synthetic media
The genome of retroviruses is made of: A. Two copies of dsRNA B. Segmented ssDNA C. Two copies of ssRNA D. Segmented ssRNA E. Two copies of ssDNA
C. Two copies of ssRNA
Which test can be used to identify Streptococcus pneumoniae? A. Bacitracin susceptibility B. Oxidase C. Coagulase D. Bile solubility E. Catalase
D. Bile solubility
Select the correct statement(s) regarding viruses. Check all that apply. A. The receptors to which animal virus attachment proteins usually bind are carbohydrates. B. The structure of plant, animal and bacterial viruses are each, fundamentally, verry different from one another. C. Viroids characteristically are composed of dsRNA. D. Carriers may have a persistent infection E. Naked and enveloped viruses both may enter the host via endocytosis.
D. Carriers may have a persistent infection E. Naked and enveloped viruses both may enter the host via endocytosis.
A 1-month-old boy developed eythema around his mouth, which then covered his body within 2 days. The skin became covered with blisters, and the top layer of epidermis was sloughed off. Which of the following is consistent with the MECHANISM of this disease? A. coagulase B. Lipase C. Endotoxin D. Exotoxin E. Phage F. Enterotoxin G. Lecithinase
D. Exotoxin
A wound specimen obtained from a 45 YO woman working with wool from a Caribbean island demonstrated a large gram-positive rod from a nonhemolytic colony with swirling projection on blood agar. The most likely method to demonstrate spores would be which of the following? A. Acid-fast stain B. Giemsa stain C. Gram stain D. Malachite green stain E. India ink stain
D. Malachite green stain
A physician working in a rural community in Russia sees a number of local residents with signs and symptoms suggestive of diphtheria. Which antibiotic should be used to treat these patients? A. Ciprofloxacin B. Chloramphenicol C. Metronidazole D. Penicillin E. Doxycycline
D. Penicillin
During a medical check-up for a new insurance policy, a 60 YO grandmother is found to be positive in the ELISA screening test for antibodies against HIV-1 infection. She has no known risk factors for exposure to the virus. Which of the following is the mots appropriate next step? A. Test the patient for Pneumocystis jiroveci infection B. Immediately begin therapy with azidothymidine C. Tell the patient that she is likely to develop AIDS D. Perform the screening test a second time E. Request that blood culture be performed in a laboratory
D. Perform the screening test a second time
Infection of the fallopian tubes can lead to infertility. Why would this be so?
Damaged tissue is replaced by scar tissue, which can block a fallopian tube.
Name three types of antigen-presenting cells (APC)
Dendritic cells, macrophages, and B cells
Which of the following is the current preferred anitmicrobial treatment of cutaneous anthrax? A. Aminoglycosides B. Cephalosporins C. Penicillin D. Tetracyclines E. Ciproflaxin
E. Ciproflaxin
What could a microorganism do to avoid engulfment?
Destroy C5a (a complement protein that attracts phagocytes), destroy phagocytes, attract complement regulatory proteins to avoid the opsonizing effects co complement.
Which of the following most accurately ddescribes the therapy available for the prevention and treatment of Corynebacterium diphtheriae? A. DTaP booster vaccination only B. Antitoxin only C. Antimicrobial therapy for prophylaxis only D. Antimicrobial therapy (Penicillin) and antitoxin only E. Antimicrobial therapy and prophylaxis, antitoxin, and DTaP
E. Antimicrobial therapy and prophylaxis, antitoxin, and DTaP
A 54 YO WM develops an infection at his surgical incision site 2 days after cardiac surgery. The site is characterized by swelling, erythema, and purulent drainage around the sutures. Culture of the drainage is performed, and beta-hemolytic colonies grow on aerobic blood agar plates after 24h of incubation. Which enzyme is an important virulence factor and diagnostic marker for this organism? A. LEcithinase B. Endotoxin C. Exotoxin A D. Catalase E. Coagulase
E. Coagulase
The herpesviruses are able to evade the host's immune response by which mechanism? A. Block interferon production B. Prevent CD8 T-cell killing C. Block IL-1 and TNF-mediated inflammation D. Cause genetic change after infection E. Establish latent infections
E. Establish latent infections
The lungs of individuals with cystic fibrosis are co-colonized with Staph aureus and which of the following bacteria? A. Mycobacterium avium intracellulare (MAI) B. Legionella pneumophila C. Aeromonas hydrophila D. Haemophilus influenzae E. Pseudomonas aeruginosa
E. Pseudomonas aeruginosa
Describe the clonal selection theory.
Each B cell is programmed to recognize a single epitope, and therefore antigens with that epitope "select" which B cells will respond. In response to this selection, the B cells divide, producing clones that recognize the same epitope.
Describe two changes in cells undergoing apoptosis
Enzymes cut the DNA and portions of the cell bud off
A 12 YO girl is evaluated for malaise, sore throat, and exudative pharyngitis. Examination indicates the presence ofa pseudomembrane covering the tonsils, uvula, and palate and a fever of 39^C. Further history indicates that her parents prevented her from receiving the standard childhood immunizations. Which of the following describes the vaccine that is used for the standard childhood immunization to prevent the disease described by these symptoms? A. Live, attenuated lysogenic virus B. Hyaluronic acid capsule conjugated to inactivated exotoxin C. Inactivated lysogenic virus D. Inactivated endotoxin E. Carbohydrate conjugated to protein F. Inactivated exotoxin
F. Inactivated exotoxin
During which pages of the bacteriala growth curve does a bacterial population become much more resistant to harmful conditions? A. Early death phase B. Stationary phase C. Early log phase D. Exponential phase E. Lag phase F. Late log phase
F. Late log phase
A 27 YO HIV+ male has experienced malaise over a 2-week period. On examination he is febrile and short of breath. A chest radiograph shows bilateral diffuse pulmonary infiltrates and a bronchoalveolar lavage revealed delicate 5-8 mm cystic therapy. the most likely etiologic agent is ______________________. A. Chlamydophila psittaci B. Chlamydophila pneumoniae C. Legionella pneumophila D. Candida E. Coccidioides F. Pneumocystis
F. Pneumocystis
The use of bar soap in the hospital waas indicated as a major source of nosocomial infection with a gram-negative bacillus resistant to most antibacterial agents. The microbe was oxidase-positive and nonfermentive. Which of the following the likely agent? A. Acinetobacter baumanni B. Escherichia coli C. Salmonella enterica D. "Iraqibacter" E. Vibrio cholerae F. Pseudomonas aeruginosa G. Bacillus cereus
F. Pseudomonas aeruginosa
How is lymph formed?
Fluids and leukocytes from the tissue enter the lymphatic system, becoming lymph.
In opsonization with IgG, why is it important that phagocytes recognize the antibodies only after they bind antigen?
For one thing, if phagocytes attached to antibodies before they attached to antigen, the antibodies would no longer diffuse in tissue fluids and therefore would not neutralize antigens. Also, the binding would block the Fc portion of antibodies, so the molecules could never activate the complement system or induce ADCC.
Identify the usual etiology of "cold sores". A. HSV-2 virus integrated in the DNA of sacral ganglions B. A naked dsDNA virus that multiplies in the epithelial cells. C. Human herpes virus type 6 (betaherpesviridae) D. Epstein-Barr virus (EBV) E. HHV-3 F. Varicella-Zoster virus (VZV) G. An enveloped dsDNA virus that forms episomal latent infection in cervical ganglions
G. An enveloped dsDNA virus
Which maternal antibody classes protect a breast-fed newborn?
IgG and IgA
Why is IgM particularly effective at cross-linking antigens?
It is a pentamer, and therefore has 10 antigen-binding sites.
How does the mucociliary escalator protect against infection?
It moves microbes out of the airways.
How would mucosal immunity prevent diarrheal disease?
It neutralizes virus and toxins in the intestinal tract and prevents microorganisms from traveling through mucus and adhering to the mucous membranes, thereby blocking the action of intestinal pathogens.
From a pathogen's standpoint, why would it be beneficial to bind regulatory proteins that inactivate C3b?
It prevents both opsonization and complement activation.
What is the function of a colony-stimulating factor (CSF)?
It promotes the development of certain cell types.
How are macrophages related to monocytes?
Macrophages descend from monocytes; the monocytes circulate in blood, and as they enter the tissues, they develop into macrophages.
The body's own cells do not trigger the alternative pathway of complement pathway activation. How come?
Molecules in host cell membranes bind regulatory proteins that will inactivate any C3b molecules that attach to the membrane.
Which type of granulocyte is the most abundant?
Neutrophils
Would a denatured antigen be expected to have the same epitopes as its native (undenatured) counterpart?
No, because epitopes can be three-dimensional shapes, and those are destroyed when the protein is denatured.
What molecules might pattern recognition receptors recognize?
PTG, LPS, flagelin
List two sensor systems of the innate defenses.
Pattern recognition receptors Complement system
How does a phagolysosome differ from a phagosome?
Phagolysosomes have fused with lysosomes, and therefore they contain the enzymes and toxic substances of lysosomes.
What are Peyer's patches?
Secondary lymphoid organs where cells of the immune system gather to encounter material from the intestinal tract.
Why would macrophages have TLRs in their endosomal membranes?
So they can determine if they have engulfed microbial invaders (as opposed to normal host components).
What are endogenous and exogenous pyrogens?
Substances that induce fever; cytokines are endogenous pyrogens whereas microbial products are exogenous pyrogens
If a cell produces antiviral proteins, what happens to that cell when those proteins encounter long dsRNA?
The cell shuts down protein synthesis, eventually leading to apoptosis.
Syphilis was once treated by infecting the patient with the parasite that causes malaria, a disease characterized by repeated bouts of fever, shaking, and chills. Why would this treatment cure syphilis?
The high fever that develops as a result of malaria is above the optimum growth temperature of the bacterium that causes syphilis.
How is the strategy of the cell-mediated response different from that of the humoral response?
The humoral response is geared towards eliminating invaders that are in body fluids whereas the cell-mediated is directed towards eliminating invaders that are within host cells.
What is a ligand?
The molecule that binds to a given receptor
How would damage to the ciliated cells of the respiratory tract predispose a person to infection?
The mucociliary escalator would no longer function properly, so microbes wouldn't be removed from the airways.
Describe the dual roles played by some types of phagocytes.
They destroy invaders and also communicate with components of the adaptive immune system to enlist their help.
Why is it important that B cells and T cells are activated before they can mount a response against antigen?
To ensure that they do not mount a response against the body's own tissues
What role does C3b play in opsonization and complement system activation?
When many molecules of C3b are bound to a particle, macrophages can more easily engulf the particle (opsonization); when even a few molecules of C3b are bound to a particle, other complement components can bind, leading to activation of the complement system.