Combined extract of heated 4T1 and a heatkilled preparation of lactobacillus Casei in a mouse model of breast cancer

Background: the adjuvanticity potential of lactobacillus casei was first suggested in an old survey. the present study was designed to investigate the efficacy of a new immunotherapy against breast cancer made by mixing an extract of heated 4t1 mammary carcinoma cell line and a heat-killed preparation of lactobacillus casei. methods: female balb/c mice (6–8 weeks old,n=40) were challenged subcutaneously in the right flanks with 4t1 cells. when all the animals developed a palpable tumor,they were allocated to 4 equal groups and immunotherapy was initiated. the tumor-bearing mice in the experimental groups received the extract of heated 4t1 or heated lactobacillus casei and/or a combination of both,twice at a 1-week interval. the mice in the control group received phosphate-buffered saline. one week after the last immunotherapy,one half of the mice were euthanized to determine the immune response profile. the remaining animals were kept until death occurred spontaneously. results: the animals receiving the combined treatment significantly showed more favorable survival curves and slower rates of tumor development than the tumor-bearing mice receiving only the heated 4t1 and/or the negative control mice. the combined immunization significantly amplified the production of nitric oxide and the cytotoxicity of natural killer cells in the spleen cell culture of the tumor-bearing mice. moreover,the combined immunotherapy significantly increased the secretion of ifn-γ and conversely diminished the secretion of il-4 and tgf-β in the splenocyte population compared to the splenocytes from the other groups. conclusion: the combined immunotherapy with heated 4t1 cells and lactobacillus casei conferred beneficial outcomes in our mouse model of breast cancer. © 2017,shiraz university of medical sciences. all rights reserved.