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NBME 16 Answers

nbme16/Block 3/Question#30 (7.5 difficulty score)
A 24-year-old woman was stung on her right ...
Influx of macrophages producing interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alphaπŸ”
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 +1 
submitted by iury_r1beiro(3),

Hypersensisitivity Type I: LATE RESPONSE.

Immediate (minutes): antigen crosslinks preformed IgE on presensitized mast cells

immediate degranulation > release of histamine (a vasoactive amine) and tryptase (a marker of mast cell activation).

Late (hours): chemokines (attract inflammatory cells, eg, eosinophils) and other mediators (eg, leukotrienes) from mast cells > inflammation and tissue damage.

FA 2020 P 112




 +0 
submitted by biochemgirl22(4),

(FA 2020 Pg 214)

Acute inflammation + Vasodilation of vasculature and increased endothelial permeability. IL1, IL6, and TNFa are all involved in acute inflammation.

aakb  it literally says "Macrophages predominate in the late stages of acute inflammation (peak 2–3 days after onset)" this question is asking for 6 hrs after onset +2  



 +0 
submitted by drjo(0),

This (late bee sting rxn) is describing an Arthus reaction (localized Type III HSR) + IgG immune complexes accumulate at site --> mast cell degranulation --> Neutrophil recruitment + IgG immune complexes also stimulate macrophages to release inflammatory cytokines (IL-1, IL-6, TNF-a) and chemokines (IL-8) --> Neutrophil recruitment result in edematous indurated lesion

Timeline for arthus reaction bee sting: 1-8 hours, generally: 6-12 hours vs Late phase Type 1 HSR 2-4 hours

https://www.sciencedirect.com/topics/immunology-and-microbiology/arthus-reaction