ABSTRACT
Antitumor effect of lactic acid bacteria [LAB] have been shown in many studies, this effect maybe as a result of immunomodulatory properties of these bacteria. In present work, we have studied the effect of Lactobacillus casei on the tumour growth rate in BALB/c mices bearing breast cancer. 6-8 week-old In-bred BALB/c mice, each weighing 25-30 g, were used. There are two experimental group consisted of 9 mices that they were used as controls in each assay. The L.casei ATCCT 39392 strain used in this study was inoculated in MRS broth and cultivated for a day at 37 °C under anaerobic conditions, collected by centrifugation and resuspend in PBS. After preparation of proper amount of these suspension it was orally administered to the mice with a gastric feeding, Control mice received an equal volume of PBS in duration of study. Results of this study showed that oral administration of L.casei can inhibit the tumour growth and increased the local inflammation in DTH assay as a result of increase in immune responses efficiency. In conclusion oral administration of Lactobacillus casei may regulate immune responses skewed Th1 balance and maybe helpful for cancer immunotherapy, but further studies is needed to investigate the other mechanisms of this effect