Pre-relapse blood passed through a 90-day door and a 150-day door

From the raw draw to the analysed set

The peer-reviewed observational study used routine blood from the CLIMB longitudinal MS cohort at Brigham and Women's Hospital. The authors screened stored samples from 85 participants and took 15 people into the first single-cell discovery set. A pre-relapse tube is blood from a visit that looked clinically stable at the time and was followed by a relapse; that label is stuck on afterwards.^[1]

The RNA door is 90 days; flow cytometry and RT-qPCR use 150 days. A remission sample is blood drawn at least 100 days after a prior relapse and at least 180 days before a later one, with clinical and imaging stability. 52 PBMC vials covering 42 unique patient timepoints went across 28 wells in 8 batches. The same cohort can therefore mint two different 'before' sets under two calendar rules.^[1]

What was measured is peripheral transcript, not the lesion

Single-cell and bulk transcription found host genes responsive to EBV lytic-reactivation factors enriched in monocytes and B cells up to 3 months before relapse. RT-qPCR confirmed elevated EBV LMP-1 transcripts in pre-relapse B cells. Flow cytometry showed expansion of CD11c+ atypical B cells displaying the EBV surface protein gp350.^[1]

The authors themselves write that how this peripheral activation relates to central-nervous-system lesion formation remains to be established. Overlap with GWAS loci and EBNA-2-bound enhancers suggests inherited risk and virus-responsive programs can share regulatory elements; that does not show the lesion is produced by EBV. The design is an observational time atlas, not an assignment experiment.^[1]

The number a repeat has to match

Discovery sits on a subset of 15 people from a screen of 85. Batches number 8, wells 28. A second lab that wants the same signature has to lock the pre-relapse window to one number before seeing the cells, then find LMP-1 and gp350 expansion inside that locked set. Leave 90 and 150 days as separate doors and 'before' remains the investigator's chosen gate.^[1]

The signature can be cleanly measured and still fail to explain the lesion: viral transcription can travel as a passenger with relapse. One study. Until a repeat hits through the same door in an independent cohort, this remains a hypothesis.^[1]