WBR0141

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Author [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]]
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, and can be divided into four 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 involved in the rolling phase of extravasation.]]
Answer B AnswerB::ICAM 1
Answer B Explanation [[AnswerBExp::ICAM-1 is involved in the tight binding of neutrophils to the endothelium.]]
Answer C AnswerC::PECAM 1
Answer C Explanation [[AnswerCExp::PECAM-1 is involved in diapedesis, which is the migration of the neutrophils across the endothelial cells.]]
Answer D AnswerD::C5a
Answer D Explanation [[AnswerDExp::C5 a is involved in the migration of leykocytes through the interstitum towards the site of inflammation.]]
Answer E AnswerE::Interleukin 8
Answer E Explanation [[AnswerEExp::Interleukin 8 is involved in the migration of leukocytes through the interstitium towards the site of inflammation.]]
Right Answer RightAnswer::C
Explanation [[Explanation::PECAM-1 is involved in diapedesis, which is the migration of the neutrophils across the endothelial cells.

The four steps of extravasation are:

  1. Margination and rolling
  2. Tight-binding
  3. Diapedsis: the migration of the neutrophils across the endothelial cells.
  4. Migration: the movement of neutrophils through the interstitium to the location of the infection, guided by C5a, IL-8, kallikrein, and platelet-activation factors, the signalling mediators.

Educational Objective: PECAM 1 is involved in diapedesis, which is the migration of the leukocytes across endothelial cells.
References: First Aid 2014 page 224]]

Approved Approved::Yes
Keyword WBRKeyword::Inflammation, WBRKeyword::Diapedesis, WBRKeyword::Leukocyte, WBRKeyword::Leukocyte adhesion, WBRKeyword::Endothelium, WBRKeyword::Endothelial cell
Linked Question Linked::
Order in Linked Questions LinkedOrder::