TABLE 2.

I-309 and SDF-1α inhibit fusion of human thymocytes with X4 and X4R5 envelope-expressing cells^a

Cells	Envelope	Chemokine	Dose (μg/ml)	Mean no. of syncytia ± SEM	% Inhibition
Thymocytes	IIIB	None		271 ± 12
		SDF-1	2	137 ± 25	50
		I-309	2	172 ± 26	38
		SDF-1 + 1-309	2 + 2	73 ± 2	74
		RANTES	2	261 ± 2	5
	RF	None		331 ± 15
		SDF-1	2	135 ± 15	59
		I-309	2	200 ± 32	40
		SDF-1 + I-309	2 + 2	30 ± 3	91
		RANTES	2	338 ± 22	0
	SF2	None		110 ± 7
		SDF-1	2	59 ± 12	47
		I-309	2	79 ± 11	28
		SDF-1 + I-309	2 + 2	28 ± 7	75
		RANTES	2	104 ± 4	0
	89.6	None		82 ± 1
		SDF-1	2	35 ± 1	68
		I-309	2	60 ± 12	27
		SDF-1 + I-309	2 + 2	23 ± 3	72
		RANTES	2	84 ± 16	0
PM1	IIIB	None		387 ± 41
		SDF-1	1	36 ± 17	91
		I-309	1	449 ± 43	0

^aThymocytes or PM1 cells were incubated with chemokines at the indicated concentrations at 37°C. After 1 h of incubation, cells were mixed (at a 1:1 ratio) with effector cells infected with recombinant vaccinia viruses expressing IIIB, RF, SF2, or 89.6 envelopes. Syncytia were scored after 4 to 5 h. Percent reduction in syncytium formation was calculated as described in Table 1, footnote a. Data represent two experiments.