Immunomodulation by treatment with Lactobacillus casei strain Shirota.

Lactobacillus casei strain Shirota (LcS) has been shown to have potent anti-tumour and anti-metastatic effects on transplantable tumour cells and to suppress chemically-induced carcinogenesis in rodents. In particular, intrapleural (i.pl.) administration of LcS into tumour-bearing mice has been shown to effectively inhibit the growth of tumour cells in the thoracic cavity and to significantly prolong survival time. Also, i.pl. administration of LcS has been shown to induce the production of several cytokines, such as IFN-gamma, IL-1beta and TNF-alpha, in the thoracic cavity of mice, resulting in the inhibition of tumour growth and increased survival. On the other hand, oral administration of LcS has been shown to inhibit the growth of implantable tumour cells in rodents, and to restore the decreased mitogenic response of tumour-bearing mice. Administration of LcS has also been shown to inhibit chemically-induced bladder cancer in rodents. These findings suggest that treatment with LcS has the potential to ameliorate or prevent a variety of diseases through modulation of the host's immune system, specifically cellular immune responses.