Caracterização de modelo de imunossupressão com ciclofosfamida em camundongos portadores ou não de tumor de ehrlich

Abstract

Cyclophosphamide is a drug widely used in the treatment of cancers. Due to its non-specific antiproliferative action, it also acts as an immunosuppressant, an effect that is present in patients treated by this drug. In this context, it is opportune to develop preclinical models of immunosuppression concomitant with the experimental ones of cancer, for several purposes. Thus, the objective of this study was to characterize a model of immunosuppression with cyclophosphamide in mice with or without Ehrlich tumor. For this, male mice of the Swiss strain, aged 3 to 4 months, received in the right ear 5x105 Ehrlich tumor cells or PBS (20μL). From the second day after the inoculum, the animals received cyclophosphamide (25mg/kg) daily, intraperitoneally, for 10 days. Animals and feed were weighed at the beginning and at the end of treatment. On the twelfth day after the inoculum, the animals were euthanized and the ears were removed for macroscopic and histological analysis. In addition, the cells of the blood, peritoneum, bone marrow and spleen were quantified. Splenic immunophenotyping and evaluation of hydrogen peroxide (H2O2) were also performed. Initially the antitumor effect of cyclophosphamide was confirmed in the model used and the reduction of inflammatory infiltrate and necrosis in the ears with tumor was confirmed. As an immunosuppressive effect, this drug caused reduction of feed intake, animal weight, leucopenia, medullary aplasia and reduced the number of splenocytes. Cyclophosphamide, alone, induced a decrease in the number of B lymphocytes in the spleen. However, in animals with tumor, cyclophosphamide induced a decrease in all analyzed populations. In addition, there was a decrease in B lymphocytes, activated cytotoxic T, NKT cells and macrophages when compared to tumor-bearing and tumor-free animals, both treated by this drug. Although cyclophosphamide also reduced the cells in the peritoneum, it was verified that the functional capacity of these cells was not affected, since there was a high production of H2O2 after stimulation with PMA. These results allow us to conclude that the protocol characterized in this study can be used as an efficient pre-clinical model of immunosuppression in animals with or without tumor, considering its effects on the cellularity of lymphoid organs and peripheral tissues.