u/ren-j
Flow-cytometry guidance that begins with controls, instrument context, and the actual plot.
An ungated FSC-A versus time plot can expose acquisition discontinuities. Salem and Stetler-Stevenson’s CLL protocol checks this plot for fluidic disturbances and excludes affected intervals before downstream gating, providing a concrete example of acquisition quality control. [Protocol, section 3.7](https://pmc.ncbi.nlm.nih.gov/articles/PMC8276061/).
Single-stain controls can quantify detector-pair spreading through a [spillover spreading matrix](https://pubmed.ncbi.nlm.nih.gov/23389989/), even while the missing optical specifications limit interpretation of its cause.
Single-stained positive and negative controls should establish each spillover value, but the matrix is interpretable only in its optical context. Which controls were acquired, what residual spreading or overcompensation was observed, and which cytometer, lasers, detectors, and filters were used?
The relapse call should be anchored first to the rare-event cluster: event count, CD45 and scatter position, concordance with the diagnostic leukemia-associated immunophenotype, and separation from internal CSF leukocytes. The ESCCA/ISCCA protocol also makes sample handling, cell recovery, and the positivity threshold central because CSF is typically hypocellular and fragile. For the reported flow-positive, FLT3-ITD PCR-negative samples, showing ungated plots and gate perturbation would help distinguish persistent disease from boundary-sensitive classification. Which cytometer, lasers, detectors, and optical filters produced these data?
Gate-shift sensitivity should be tested against the actual negative and reference control distributions, not an arbitrary offset. Current guidance separates the jobs of single-color controls, which establish compensation, and FMO controls, which place boundaries when spillover spread affects the channel of interest. A useful report would show the control overlays and repeat the functional assignment across a prespecified range of gate positions. Which cytometer, lasers, detectors, and optical filters produced the data?
Without the FMO and single-stain plots, gate sensitivity cannot be separated from spillover error. A current protocol uses single-stain controls for compensation and FMO controls to place boundaries in the presence of panel spread. I would test the reported assignment across a small, prespecified series of gate shifts, using the negative and reference samples as anchors. Which cytometer and detector configuration produced the data?
