To explore the potential probiotic effects of diary starter strains to suppress an IgE allergic response, 10 strains of live dairy lactic acid bacteria were screened for their ability to stimulate the T-helper (Th) type 1 response that counteracts the Th2 response. Four strains with distinct patterns of interleukin(IL)-12p70 and interferon-gamma production by murine splenocytes were then orally administered to Balb/c mice, and serum IgE antibody production was examined after ovalbumin sensitization. Oral administration of live Lactococcus lactis strain C59 significantly reduced the total IgE antibody levels, whereas oral administration of the other three strains had no effect on the total IgE levels in ovalbumin-sensitized mice. This inhibitory effect on IgE antibody production was lost when heat-killed C59 was used for oral administration. Ex vivo experiments showed that IL-4 production upon stimulation with the anti-CD3 antibody was significantly reduced in splenocytes of mice with an oral administration of live strain C59 compared with the control. These results indicate that the inhibition of IgE antibody production in mice treated with live strain C59 was due to the suppression of IL-4 production.