TABLE 6.

IL-2 and anti-LPS IgG responses in animals immunized once, twice, or three times with strain WR201 bacteria^a

Inoculum	IL-2 (pg/ml ± SD)	Anti-LPS IgG (OD ± SD)
Saline	0 ± 0	2 ± 0
WR201
1 ×	33 ± 16b	1,448 ± 1,330b
2 ×	205 ± 148b,c	7,898 ± 4,572b
3 ×	188 ± 114b,c	3,302 ± 1,680b

^aGroups of five animals were orally immunized with 10¹¹ CFU of WR201 once, twice, or three times at 8-week intervals. Sham-immunized control animals received saline three times. Serum and spleen cells were obtained 8 weeks after the last dose of vaccine. Serum anti-LPS IgG levels were determined by ELISA. IL-2 content levels were measured by ELISA in supernatant fluids from spleen cells cultured for 24 h with RFBL. Data are expressed as means ± SD. The significance of differences between groups was determined by ANOVA with Tukey's simultaneous pairwise comparisons on log-normalized data.

^bSignificantly different from sham-immunized (saline) group results.

^cSignificantly different results from those seen with mice immunized once.