Table 3. Scoring cells treated with standard pertussis toxin concentrations for CHO cell clustering by microscopy and xCELLigence.

Method	Experiment	Standard PT (IU/mL) a								PT Endpoint Conc (IU/mL)	PT Median endpoint Conc (IU/mL) (expected variability range)
		2	1	0.5	0.25	0.125	0.063	0.031	0.016
Microscopy	1	+	+	+	+	-	-	-	-	0.25	0.25 (0.125–0.5)
	2	+	+	+	+	-	-	-	-	0.25
	3-replicate 1	+	+	+	+	+	-	-	-	0.125
	3-replicate 2	+	+	+	+	-	-	-	-	0.25
	4-replicate 1	+	+	+	+	+	-	-	-	0.125
	4-replicate 2	+	+	+	+	+	-	-	-	0.125
	5-replicate 1	+	+	+	+	-	-	-	-	0.25
	5-replicate 2	+	+	+	+	-	-	-	-	0.25
xCELLigence	1	+	+	+	+	+	-	-	-	0.125	0.125 (0.063–0.25)
	2	+	+	+	+	+	-	-	-	0.125
	3-replicate 1	+	+	+	+	+	-	-	-	0.125
	3-replicate 2	+	+	+	+	+	-	-	-	0.125
	4-replicate 1	+	+	+	+	+	-	-	-	0.125
	4-replicate 2	+	+	+	+	+	+	-	-	0.063
	5-replicate 1	+	+	+	+	+	-	-	-	0.125
	5-replicate 2	+	+	+	+	+	-	-	-	0.125

^a Results after 48 h of incubation.

“-”: Negative for cell clustering (Microscopy: ≥ 80% cell clustering per well; xCELLigence: Relative cell index ≤ 65%).

“+”: Positive for cell clustering (Microscopy: < 80% cell clustering per well; xCELLigence: Relative cell index > 65%).

Endpoint Conc: Endpoint concentration, last concentration of standard PT to show a positive response.

Expected variability range: Plus or minus one two-fold dilution of the median.