TABLE 2.

IFN-γ secretion by spleen cells from BALB/c mice immunized with different plasmids upon in vitro restimulation with the recombinant protein His-65kDa

Plasmida	IFN-γ concn (ng/ml)b
	No antigen	Rec. TS	Rec. His-65kDa
			No Ab	Rat IgG	Anti-CD4 MAb	Anti-CD8 MAb	Anti-CD4 and anti-CD8 MAbs
pcDNA3	<0.2	0.27 ± 0.01	<0.2	<0.2	<0.2	<0.2	<0.2
pclone9	<0.2	<0.2	5.82 ± 0.28c	5.28 ± 1.55	0.84 ± 0.29d	3.91 ± 0.59e	1.12 ± 0.59d
pSPclone9	<0.2	NTf	4.16 ± 1.34c	4.79 ± 0.95	0.89 ± 0.21d	3.24 ± 0.50e	0.56 ± 0.07d
pIgSPclone9	<0.2	0.43 ± 0.13	3.29 ± 1.19c	3.45 ± 0.54	0.65 ± 0.07d	2.91 ± 0.33e	0.52 ± 0.07d

^aBALB/c mice were immunized with the indicated plasmid as described in Materials and Methods. Two weeks after the last immunization, pooled spleen cells were collected from three mice.

^bSpleen cells were stimulated in vitro with 10 μg of recombinant (Rec.) protein His-65kDa or recombinant TS per ml in the presence or absence of 10 μg of rat IgG per ml or with anti-CD4 or anti-CD8 MAb or anti-CD4 and anti-CD8 MAbs. The concentration of IFN-γ was estimated in cell culture supernatants, and results are expressed as averages of triplicate cultures ± SDs. This experiment was reproduced three times with identical results. No Ab, no antibody.

^cSignificantly different from values for the supernatants of cells cultured in the absence of the recombinant protein His-65kDa or in the presence of recombinant TS (P < 0.01 by the Student t test).

^dSignificantly different from values in the supernatants of cells cultured in the presence of rat IgG (P < 0.01 by the Student t test).

^eNot significantly different from values in the supernatants of cells cultured in the presence of rat IgG (P > 0.05 by the Student t test).

^fNT, not tested.