Immunotherapy of Metastatic Mouse Breast Cancer by Adherent Splenocytes Pulsed With Extracts of Heated Tumor Cells and Lactobacillus Casei

Flask-adherent Splenocytes (SACs) fulfill antigen-presenting cell requirements of acquired immune responses. This study was done to evaluate the efficacy of new immunotherapy against breast cancer made by SACs pulsed with the extract of heated 4T1 cells and Lactobacillus casei, as a probiotic.

Mammary carcinoma was induced by injection of 4T1 cell line in the flank of female Balb/c mice. The first SACs therapy was started on day 11 after tumor induction when all animals had developed a palpable tumor. SACs therapy was done twice at a 10-day interval.

Mice with mammary tumors received SACs pulsed with combined heated 4T1 cells and L. casei determined a more desirable survival curve and a slower rate of tumor development compared to the other groups. At least 20% of the group receiving combined immunotherapy were alive by day 58. Those mice receiving SACs pulsed with the Lysate of heated tumor cells died by day 45.The maximum survival of other mice was up to 38 days after tumor induction. Moreover, SAC pulsed with combined agents significantly amplified the secretion of Interferon-γ (IFN-γ), and conversely reduced the secretion of Transforming growth factor-β (TGF-β) and Interleukin 4 (IL-4) in the splenocyte population compared to splenocytes from other groups. Combined immunotherapy increased the expression of p53 and caspase 3 genes and reduced the exertion of BCL2 more than other immunotherapy protocols.

Immunotherapy with SACs pulsed with heated 4T1 cells and L. casei promotes beneficial outcomes in the mouse model of breast cancer.