TABLE 1.

Comparative CTLA4-Ig and antibody-dependent capture of lentiviral pseudotypes^a

Treatment	Titerb	Fold increase	% Capture
V+LV.B7.1bla
Control	2.06 ± 0.3
100 μg CTLA4-Ig	1,330 ± 57	645	81
175 μg anti-B7.1	1,130 ± 153	548	60
V + LV.LNbla
Control	1.3 ± 0.46
175 μg anti-NGFR	866 ± 115	666	52
V + LV.bla
Control	0.34 ± 0.07
175 μg anti-NGFR	0.16 ± 0.05	0
A + LV.B7.1bla
Control	0.72 ± 0.015
100 μg CTLA4-Ig	4,560 ± 288	6,307	95
175 μg anti-B7.1	2,900 ± 265	4,011	80
A + LV.LNbla
Control	0.57 ± 0.011
175 μg anti-NGFR	2,070 ± 250	3,600	0
A + LV.bla
Control	0.09 ± 0.01
175 μg anti-NGFR	0.16 ± 0.07	1.7

^aTiters of 293T cell-derived lentiviral vector supernatants (LV.B7.1bla, LV.LNbla, and LV.bla), pseudotyped with VSV-G (V) or amphotropic (A) envelopes, were determined on K562 cells (in 4 μg/ml Polybrene) either before (control) or after capture and 100-fold concentration, using CTLA4-Ig, anti-B7.1 antibody, or anti-NGFR antibody-conjugated PMP. The concentrates and the depleted supernatants remaining after the removal of the PMP were used to infect K562 cells to determine the efficiency of both concentration (fold increase) and capture (percent capture).

^bTiters are shown as 10⁶ CFU per milliliter for VSV-G envelopes and 10⁵ CFU per milliliter for amphotropic envelopes.