Proliferation responses of mouse lymphocytes. Groups of mice were intraperitoneally immunized twice (↑) with PLG-rSAG1 microparticles (■ ), rSAG1 (Vet L-10)(● ), soluble rSAG1 alone (□ ), PLG (◊ ), or PBS (○ ). After priming, TsoAg-stimulated spleen lymphocytes were prepared from three mice per group every two weeks and their subsequent proliferation responses were analyzed and expressed as stimulation index (SI) values. Results were presented as the mean of SI values ± SD. *P<0.05 when comparing the PLG-rSAG1 group to the rSAG1 (Vet L-10) group.