Comparación de la actividad citotóxica de linfocitos T en células tumorales con diferente expresión HLA-I

Abstract

Cancer is a very heterogeneous disease whose incidence and mortality have been increasing during the last decade. However, despite the fact that the immune system is capable of recognizing and destroying malignant cells, tumors continue to grow and invade, due in part, to the fact that immune pressure causes tumor variants capable of escaping control of the immune response to be generated. . One of the strategies most commonly used by tumors to escape immunity is the deregulation of the expression of molecules of the major Histocompatibility class I complex (in human HLA), the molecule responsible for presenting endogenous antigens to T lymphocytes. cytotoxic (CTL). Tumor-associated antigens (TAA), being endogenous, occur in these molecules to be recognized by CTL, through their T cell receptor (TCR). Consequently, CTL is activated to generate a cytotoxic immune response capable of killing the tumor cell. Currently, immunotherapy is one of the most promising therapeutic strategies for the treatment of cancer, since its action is not directed to the destruction of tumor cells but to the strengthening of the immune system so that it is this, who destroys the cells tumor Advances in the knowledge of tumor immunology have allowed the development of different types of immunotherapies, many of which are based on the activation of T lymphocytes, such as the transfer of adoptive T cells or stimulated dendritic cells in vitro and re -injected to the patient, or in blocking the checkpoints of the immune response as a strategy to stimulate a specific T response, or to prevent the inactivation of activated T lymphocytes. Unfortunately, during the development of the tumor, multiple mechanisms of evasion of the immune response are used by the tumor cells to escape the immune control, the most frequent being the altered expression of HLA-I on the surface of the tumor cells. Many molecular events can trigger defects in the expression of HLA-I, including defects in the antigenic processing and presentation machinery (reversible), which can be corrected by the administration of interferon, or structural defects (irreversible) the genes that code for the β2-microglobulin (β2m) or HLA heavy chain, defects that can only be corrected by gene therapy. In this work the cytotoxic activity of CD8 + T lymphocytes against the tumor cell lines SiHa and MDA-MB-231, of cervical cancer HPV-16 + and breast cancer respectively was evaluated. By means of a cytotoxicity assay using autologous tumor lysate (from the cell lines themselves), the antigen-specific cytotoxic activity of allogenic T lymphocytes expressing HLA-A * 02: 01 and HLA-B * 44: 02 was evaluated. To evaluate the cytotoxic activity, the HLA phenotype of the cell lines that were used for the cytotoxicity assay was taken into account. The SiHa cell line is homozygous and does not express HLA-A * 02: 01 or HLA-B * 44: 02, while the MDA-MB-231 cell line expresses HLA-A * 02: 01. The cytotoxic activity will be determined by the expression of cytokines (INF and TNF); proteins of early apoptosis CD107a (LAMP-1), CD107b (LAMP2) and cytotoxic proteins such as perforin and granzyme.