Gating hierarchy
plot(gh)

Gates
plotGate(gh)

Markers/panel
pData(parameters(fr))[-(1:3),1]
## [1] "TNF" "CD69" "IL" "CD3" "IFN" "CD4" "Aqua" "CD8"
Samples
nrow(pd)
## [1] 2470
Animals
pd[, length(unique(`Animal ID`))]
## [1] 100
Time Point
pd[, unique(`Time Point`)][-c(7:9)]
## [1] "Week 0" "Week 10" "Week 25" "Week 32" "Week 52" "-2" "51"
Stimulation
pd[, unique(`Stim`)]
## [1] "DMSO" "Gag-mac239" "Gag-E543" "Env-mac239" "Env-E543"
Group (Not sure if it stands for treatment group)
pd[, unique(`Group`)]
## [1] "1" "2" "3" "4" "PARI"