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Augmentation of Cellular Immunity and Reduction of Influenza Virus Titer in Aged Mice Fed Lactobacillus casei Strain Shirota

Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi, Tokyo 186-8650, Japan¹

Received 25 July 2001/ Returned for modification 25 September 2001/ Accepted 24 October 2001

We investigated whether oral administration of Lactobacillus casei strain Shirota activates the cellular immune system and ameliorates influenza virus (IFV) titer in the nasal site in upper respiratory IFV infection by using aged mice. Natural killer activity of splenocytes and lung cells of aged mice fed an L. casei strain Shirota diet (L.casei strain Shirota group) was significantly (P < 0.01 and P < 0.05) increased compared to those fed a control diet (control group). The increases were 1.5- and 2.5-fold, respectively. In aged mice fed an XL.casei strain Shirota diet, potent induction of gamma interferon (IFN-) and tumor necrosis factor alpha (TNF-), which play a very important role in excluding IFV, was evident in nasal lymphocytes. IFN- and TNF- production increased 12- and 3.5-fold, respectively. In this model of upper respiratory IFV infection, the titer of IFV in the nasal washings of aged mice fed an L.casei strain Shirota diet was significantly (P < 0.05) lower than that in aged mice fed a control diet (10^{1.6 ± 0.6} and 10^{2.2 ± 0.5}, respectively). These findings suggest that oral administration of L.casei strain Shirota activates not only systemic cellular immunity but also local cellular immunity and that it ameliorates IFV infection.

This article has been cited by other articles:

• Yasui, H., Kiyoshima, J., Hori, T. (2004). Reduction of Influenza Virus Titer and Protection against Influenza Virus Infection in Infant Mice Fed Lactobacillus casei Shirota. CVI 11: 675-679 [Abstract] [Full Text]