Avaliação da resposta imune antitumoral em modelos experimentais induzidos a tumor de mama e submetidos a imunoterapia com linfócitos tumor infiltrantes

Abstract

Tumor infiltrating lymphocytes (TIL) are cells of the lymphoid lineage (lymphocytes) found in tumor tissues capable of promoting an efficient antitumor response against various types of cancer. In this work, we tried to understand how these cells act in murine breast cancer induced by the 4T1 cell line, which is similar to triple negative breast cancer in women, and what are the mechanisms triggered after immunotherapy with TIL. In the present study, 54 mice were divided into three experimental groups: (n=6) control group, (n=12) tumor-free group and (n=12) TIL group receiving 2 doses of immunotherapy with TIL; and for the production of immunotherapy, 24 animals were used (1 animal per inoculum), induced to murine breast cancer and after 28 days of development, the animals were euthanized and the tumor samples were mechanically dissected to collect these cells, and later cultured with IL -two. Throughout the tumor development process of the experimental groups, we measured these tumor volumes macroscopically in the 2-day interval from the seventh day of tumor induction, and we observed that immunotherapy conditioned a statistically significant decrease in tumor growth in the treated group (p<0, 0001). We analyzed both tumor and spleen by flow cytometry an increase in total T lymphocytes (CD3+), T helper (CD4+), cytotoxic T lymphocytes (CD8) and the expression and secretion of CD25, IFN-γ, IL-2, IL- 10 and TNF-α by helper T lymphocytes and cytotoxic T lymphocytes. We also observed in these two cell lines the low expression and significant secretion of CD25, IL-2, IL-10, and the high secretion of IFN-γ in tumor samples. TNF-α was highly secreted in helper T lymphocytes, but not in cytotoxic T lymphocytes, in tumor samples; in the spleen, the secretion of this cytokine was increased in both lymphocyte phenotypes. TGF-β and IL-12 were measured by ELISA in tumor cell culture supernatant and both cytokines showed high concentrations in the TIL group. Through H&E staining, we observed a significant decrease in metastatic foci in the liver in the treated group compared to the tumor group. Although the immune responses in both samples behaved differently, the immunotherapy obtained significant results against breast cancer.