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{{WBRQuestion | {{WBRQuestion | ||
|QuestionAuthor={{Rim}} | |QuestionAuthor= {{Rim}} (Reviewed by {{YD}} and {{AJL}}) | ||
|ExamType=USMLE Step 1 | |ExamType=USMLE Step 1 | ||
|MainCategory=Immunology | |MainCategory=Immunology | ||
| Line 21: | Line 21: | ||
|MainCategory=Immunology | |MainCategory=Immunology | ||
|SubCategory=General Principles | |SubCategory=General Principles | ||
|Prompt=Neutrophils are critically involved in the process of inflammation. | |Prompt=Neutrophils are critically involved in the process of inflammation. The sequence of events in the recruitment of neutrophils from the vessel lumen to the stromal compartment is called extravasation, which can be divided into four major steps. Which of the following signaling mediators is involved in the migration of neutrophils across endothelial cells? | ||
|Explanation= | |Explanation=The involvement of polymorphonuclear neutrophils (PMN) in inflamted tissue involves a series of interactions that are collectively known as extravasation. PMNs within the endothelium are first activated and flattened by weak adhesive interactions that before they are allowed to emigrate across the endothelium. Prior to activation, PMNs first undergo rolling, which is a saltatory movement of PMN along the endothelium, to locate inflammatory mediators. PMNs are then activated by local inflammatory mediators. Activation allows PMNs to acquire strong adhesive interactions with the endothelium. Following adhesion, PMNs are believed to travel mostly in a paracellular fashion and exit blood vessels in a process called diapedesis. Finally, PMNs are guided by chemotactic agents and travel through the interstitium to the site of inflammation. | ||
# Margination and rolling | In order to achieve all steps of extravasation, PMNs utilize proteins that are expressed on either the vascular endothelial cells or on the PMNs themselves: | ||
# Tight-binding | # Margination and rolling: mainly e-selectin, p-selectin, GlyCAM-1, and CD34 expressed on vascular endothelium, and Sialyl-Lewis and L-selectin expressed on PMN. | ||
# Diapedsis: | # Tight-binding: mainly ICAM-1 (CD54) expressed on vascular endothelium, and CD11/18 integrins, LFA-1, MAC-1, and VLA-4 integrin expressed on PMN. | ||
# Migration: | # Diapedsis: mainly PECAM-1 (CD31) expressed on both vascular endothelium and PMN | ||
|AnswerA=E selectin and P selectin | # Migration: mainly C5a, IL-8, LTB4, kallikrein, and platelet-activating factor expressed on vascular endothelium. | ||
|AnswerAExp=[[E selectin]] and P selectin are involved in the rolling phase of extravasation. | |AnswerA=E-selectin and P-selectin | ||
|AnswerB=ICAM 1 | |AnswerAExp=[[E-selectin]] and P-selectin are mainly involved in the rolling phase of extravasation. | ||
|AnswerBExp=[[ICAM-1]] is involved in the tight binding of [[neutrophils]] to the [[endothelium]]. | |AnswerB=ICAM-1 | ||
|AnswerC=PECAM 1 | |AnswerBExp=[[ICAM-1]] (CD54) is mainly involved in the tight binding (adhesion) of [[neutrophils]] to the [[endothelium]]. | ||
|AnswerCExp=[[PECAM-1]] is involved in diapedesis, which is the migration of the neutrophils across the endothelial cells. | |AnswerC=PECAM-1 | ||
|AnswerCExp=[[PECAM-1]] (CD31) is mainly involved in diapedesis, which is the migration of the neutrophils across the endothelial cells. | |||
|AnswerD=C5a | |AnswerD=C5a | ||
|AnswerDExp=[[C5]] a is involved in the migration of leykocytes through the interstitum towards the site of inflammation. | |AnswerDExp=[[C5]]a is mainly involved in the migration of leykocytes through the interstitum towards the site of inflammation. | ||
|AnswerE= | |AnswerE=IL-8 | ||
|AnswerEExp= | |AnswerEExp=IL-8 is mainly involved in the migration of [[leukocytes]] through the interstitium towards the site of [[inflammation]]. | ||
|EducationalObjectives=[[PECAM 1]] is involved in diapedesis, which is the migration of the leukocytes across endothelial cells. | |EducationalObjectives=[[PECAM-1]] is mainly involved in diapedesis, which is the migration of the leukocytes across endothelial cells during the process of PMN extravasation. | ||
|References=First Aid 2014 page 224 | |References=Scalia R, Lefer AM. In vivo regulation of PECAM-1 activity during acute endothelial dysfunction in the rat mesenteric microvasculature. J Leukoc Biol. 1998;64(2):163-9.<br> | ||
First Aid 2014 page 224 | |||
|RightAnswer=C | |RightAnswer=C | ||
|WBRKeyword=Inflammation, Diapedesis, Leukocyte, Leukocyte adhesion, Endothelium, Endothelial cell | |WBRKeyword=Inflammation, Diapedesis, Leukocyte, Leukocyte adhesion, Endothelium, Endothelial cell, PECAM-1, CD31 | ||
|Approved=Yes | |Approved=Yes | ||
}} | }} | ||
Latest revision as of 23:27, 27 October 2020
| Author | [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Yazan Daaboul, M.D. and Alison Leibowitz [2])]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Immunology |
| Sub Category | SubCategory::General Principles |
| Prompt | [[Prompt::Neutrophils are critically involved in the process of inflammation. The sequence of events in the recruitment of neutrophils from the vessel lumen to the stromal compartment is called extravasation, which can be divided into four major steps. Which of the following signaling mediators is involved in the migration of neutrophils across endothelial cells?]] |
| Answer A | AnswerA::E-selectin and P-selectin |
| Answer A Explanation | [[AnswerAExp::E-selectin and P-selectin are mainly involved in the rolling phase of extravasation.]] |
| Answer B | AnswerB::ICAM-1 |
| Answer B Explanation | [[AnswerBExp::ICAM-1 (CD54) is mainly involved in the tight binding (adhesion) of neutrophils to the endothelium.]] |
| Answer C | AnswerC::PECAM-1 |
| Answer C Explanation | [[AnswerCExp::PECAM-1 (CD31) is mainly involved in diapedesis, which is the migration of the neutrophils across the endothelial cells.]] |
| Answer D | AnswerD::C5a |
| Answer D Explanation | [[AnswerDExp::C5a is mainly involved in the migration of leykocytes through the interstitum towards the site of inflammation.]] |
| Answer E | AnswerE::IL-8 |
| Answer E Explanation | [[AnswerEExp::IL-8 is mainly involved in the migration of leukocytes through the interstitium towards the site of inflammation.]] |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::The involvement of polymorphonuclear neutrophils (PMN) in inflamted tissue involves a series of interactions that are collectively known as extravasation. PMNs within the endothelium are first activated and flattened by weak adhesive interactions that before they are allowed to emigrate across the endothelium. Prior to activation, PMNs first undergo rolling, which is a saltatory movement of PMN along the endothelium, to locate inflammatory mediators. PMNs are then activated by local inflammatory mediators. Activation allows PMNs to acquire strong adhesive interactions with the endothelium. Following adhesion, PMNs are believed to travel mostly in a paracellular fashion and exit blood vessels in a process called diapedesis. Finally, PMNs are guided by chemotactic agents and travel through the interstitium to the site of inflammation.
In order to achieve all steps of extravasation, PMNs utilize proteins that are expressed on either the vascular endothelial cells or on the PMNs themselves:
Educational Objective: PECAM-1 is mainly involved in diapedesis, which is the migration of the leukocytes across endothelial cells during the process of PMN extravasation. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Inflammation, WBRKeyword::Diapedesis, WBRKeyword::Leukocyte, WBRKeyword::Leukocyte adhesion, WBRKeyword::Endothelium, WBRKeyword::Endothelial cell, WBRKeyword::PECAM-1, WBRKeyword::CD31 |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |