Table 2.

Effect of increasing the total number of CpG motifs expressed on the stimulatory activity of an ODN

	% maximal response
Total no. of CpG Motifs	Prolif	IL-6	IgM	IP-10	Mean
1	30 ± 3	27 ± 2	25 ± 2	21 ± 1	25 ± 4
2	54 ± 16	38 ± 5	59 ± 14	39 ± 7	47 ± 9*
3	73 ± 13	57 ± 7	84 ± 12	50 ± 11	66 ± 13*†
4	62 ± 7	68 ± 2	88 ± 5	63 ± 1	70 ± 11*†
5	53 ± 4	56 ± 5	46 ± 2	41 ± 4	49 ± 7*

The level of immune activation induced by 1 µm of 32 different ODNs (see Table 1, series 1) was monitored in PBMC from ≥6 donors. IL-6, IgM and IP-10 levels in culture supernatants were measured by ELISA, while proliferation was measured by ³H-thymidine incorporation. The maximum background versus immune stimulation observed in the samples studied was: IL-6; 0·2 versus 6 ng/ml, IgM; 0·3 versus 15 µg/ml, IP-10; 0·1 versus 2·2 ng/ml and proliferation 1100 versus 27 100 cpm. To facilitate comparison between donors, the maximum response in each assay was set to 100, and the relative strength of each ODN then calculated by the formula: (response to ODN – background)/(maximum response – background) × 100%. The mean and std deviation for each group is shown.

^*Significantly greater than one motif, P < 0·01.

^†Significantly greater than two motifs, P < 0·01.