Acute Inflammation

Portable Network Graphics image-72A6030C05F6-1

I always had trouble remembering the steps in acute inflammation involving neutrophils. I came up with a pretty simple mnemonic and I never get a question wrong on this sequence anymore. I really liked how Pathoma describes selectins as “speedbumps” during rolling, which I included in this mnemonic. More coming soon!

More detail below:

  1. Margination – vasodilation slows blood flow in post-capillary venules – cells marginate from center of flow to periphery
  2. Rolling – speedbumps = selectins – cause PMNS to slow down
    1. P-selectin is released from Weibel-Palade bodies – mediated by histamine
    2. E-selectin is induced by TNF and IL-1
    3. Selectins bind sialyl Lewis X on leukocytes = rolling of leukocytes along vessel wall
  3. Adhesion – stops PMNs
    1. Cell adhesion molecules (-CAM) upregulated on endothelium by TNF and IL-1
    2. Integrins upregulated on leukocytes by C5a and LTB4
      1. Leukocyte Adhesion Deficiency – AR defect of integrins (CD18 subunit) = Delated separation of umbilical cord, increased circulating PMNs, recurrent bacterial infections w/o pus, protracted wound healing
  4. Transmigration (Diapedesis) and Chemotaxis across endothelium of post-capillary venules
    1. Attracted by IL-8, C5a, LTB4 and bacterial products
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