need help with your account or subscription? click here to email us (or see the contact page)
join telegramNEW! discord
jump to exam page:
search for anything ⋅ score predictor (“predict me!”)

Retired NBME 21 Answers

nbme21/Block 2/Question#32 (reveal difficulty score)
A 17-year-old boy has the acute onset of ...
Lymphocytes 🔍 / 📺 / 🌳 / 📖
tags:

 Login (or register) to see more


 +5  upvote downvote
submitted by pparalpha(93)
get full access to all contentpick a username

EBV (HHV-4) infects B cell through CD21.

Atypical lymphocytes on peripheral blood smear (not infected B cells, but reactive cytotoxic T cells).

"Mononucleosis": + monospot test (antibodies detected by agglutination of sheep or horse RBCs)

get full access to all contentpick a username
sbryant6  Atypical lymphocytes are CD8+ T cells, not CD4+. Remember that. +17
mangotango  I remember this because Infectious Mononucleosis is caused by a virus (mostly EBV, sometimes CMV) and MHC Class I functions to present endogenous antigens (e.g. viral or cytosolic proteins) to CD8+ T cells. In comparison, MHC Class II is more involved with presenting exogenous antigens (e.g. bacterial proteins) to CD4+ T cells. // FA 2019, pg 100 +3
amy  I get the atypical T cell idea, but can someone help me understand why monocyte is not elevated in mononucleosis???? BTW, there are both heterophil positive(EBV) AND heterophil negative(CMV) mononucleosis, so patient can have - monospot test and still have mononucleosis... +
drdoom  @amy mononucleosis ≠ monocytes. Mono-nucleosis refers to the increase of mono-nuclear cells (lymphocytes) in the blood, as opposed to polymorpho-nuclear or “segmented” white blood cells like neutrophils, basophils, or eosinophils—which all have their nuclei divided into 2 or more “lobes” (multilobar cells). “Mono-nucleosis” just refers to an increase in the blood of those cells with a “single, unlobulated/unsegmented” nucleus = lymphocytes. +1



 +0  upvote downvote
submitted by calvin_and_hobbes(2)
get full access to all contentpick a username

"In addition to slightly decreased platelet count..." — why are plts slightly low in EBV infection/mono?

get full access to all contentpick a username



Must-See Comments from nbme21

nosancuck on Absorption atelectasis
assoplasty on Free T4
seagull on GM2
lnsetick on Apocrine
niboonsh on NMDA receptors are blocked by Mg2+ at the ...
drdoom on Deletion of a hydrophobic amino acid ...
hayayah on HCO3− transported in the plasma
mcl on Aortic
notadoctor on Usual interstitial pneumonitis
madojo on Genital herpes
hungrybox on Obstruction of the bile duct
jambo2222 on Lung
hungrybox on Mismatch repair
hungrybox on Hydrochlorothiazide

search for anything NEW!