Mucosal Immunity Flashcards
The intestinal tract is home to a very large number of microorganisms. These organisms are necessary for host immunity and for various other physiological functions. Which of the following events is most responsible for protecting these indigenous bacteria from elimination by the host immune system?
A. The presence of protective IgA in the intestinal lumen
B. The production of bacteriocins that kill exogenous organisms
C. The down-regulation of Tollip expression on intestinal epithelium
D. The release of active alpha-defensins by Paneth cells
E. The down-regulation of TLR expression on intestinal epithelium
E. The down-regulation of TLR expression on intestinal epithelium
A 28-year-old woman complains to her family doctor that she hates eating crackers, because they always stick to the roof of her mouth. She also complains that she is unable to speak for a long period as she loses her voice and needs to drink water frequently. On examination, she is found to have developed oral thrush, and her vision is blurred. She is referred for further testing. What is the most probable tentative diagnosis? A. Zollinger-Ellison syndrome B. Sjogren’s syndrome C. Diabetes mellitus type 2 D. Hypochlorhydria
Sjogren’s syndrome - dry eyes, dry mouth condition of the oral cavity
A 39-year-old man presents with severe colitis associated with an overgrowth of Clostridium difficile in the lower bowel. What is the most likely cause of this disease? A. A stomach ulcer B. Mechanical blockage of the intestine C. Botulinum food poisoning D. Antibiotic therapy E. Excessive acid production
Antibiotic therapy
excessive use of antibiotics destroys the normal flora may lead to disease due to growth of opportunistic organisms
–> Clostridium difficile
A 29-year-old man presents to the emergency department with fever, chills, shortness of breath, and cough productive of yellow sputum. Physical examination reveals low blood pressure and elevated heart and respiratory rates; rales are heard on auscultation. A chest x-ray shows consolidation in the left lower lobe. A diagnosis of pneumonia due to Streptococcus pneumoniae is made and the man fully recovers in the following weeks. Control and elimination of the bacterium causing this man’s pneumonia was in part due to molecule(s) with the following characteristics:
” Collectins
“ Secreted by type II alveolar macrophages
“ Able to destroy microbial membranes
“ Can act as opsonins for alveolar macrophages
Which molecule(s) possess all of these characteristics?
A. Surfactant proteins A and D B. Complement proteins C. Alpha-defensins D. Lysozyme E. Immunoglobulins
A. Surfactant proteins A and D
What is the nature of the majority of intraepithelial lymphocytes found in the mucosal system? A. Th17 cell B. T regulatory cell C. Natural killer cell D. Cytotoxic T cell E. Follicular helper T cell
CTL
Which of the following cell types is responsible for antigen trancytosis for induction of an immune response in the gastrointestinal tract?
A. Microfold cell B. Dendritic cell C. Enterocyte D. Intraepithelial lymphocyte E. Macrophage
the M cell, microfold cell, a specialized epithelial cell overlying the Peyer’s patches that is able to effect transepithelial antigen transportation to dendritic cells in the subepithelial dome (SED) in a process called trancytosis.
Which of the following cell types is not able to present antigen to the Peyer's patches for induction of an immune response in the gastrointestinal tract? A. M cell B. Macrophage C. Enterocyte D. Dendritic cell
Enterocyte is not an APC
Which of the following is not considered an essential function of the normal microbiota within the mucosal system?
A. Competitive inhibition of potential pathogens
B. Deconjugation of bile salts
C. Production of antimicrobials
D. Synthesis of vitamin K
E. Induction of cytokine production
Induction of cytokine production
Respiratory epithelial cells secrete a number of molecules that are potently antimicrobial. Which molecule is able to lyse bacterial cells by inducing the formation of a pore in the bacterial membrane?
β-defensins Cathelicidins Surfactant Protein A Lysozyme Surfactant Protein D
β-defensins promote bacterial lysis via pore formation, are chemotactic for many leukocytes and promote phagocytosis.
Role of Cathelicidins
Cathelicidins possess broad spectrum antimicrobial activity against many organisms including Gram-positive and Gram-negative bacteria by the disruption of membrane integrity.
Role of Surfactant Proteins A & D
Surfactant Proteins A & D are collectins that are produced by type II alveolar cells. They promote phagocytosis and are directly bactericidal by destroying bacterial membranes.
Role of Lysozyme (Muramidase)
Lysozyme (Muramidase) is found in most secretions and is able to cleave the cell wall of Gram-positive bacteria.
What constituent of mucosal secretions is bactericidal with the ability to cleave the cell wall of Gram-positive organisms? Alpha defensins Surfactant Protein A Beta defensins Lysozyme Trypsin
Lysozyme
Which of the following is the primary function of the mucociliary escalator?
Neutralization of pathogen adhesion
Destruction of bacteria by membrane rupture
Physical removal of pathogen
Phagocytosis of pathogen
Facilitation of peristalsis
Physical removal of pathogen
Which of the following constitutes the first line of defense against invading microorganisms at the mucosae? Natural killer cells Cathelicidins Epithelium Resident macrophages Neutrophils
Epithelium
