Effects of cytostatics on the selected parameters of cell-mediated immunity in dogs

The aim of the study was to assess the effects of tamoxifen and cyclophosphamide on the selected cell-mediated immunity parameters in dogs. The study included 18 dogs aged 5-10 years. The experimental group consisted of 12 animals with neoplastic lesions classified as the first or second staging group (according to the WHO TMN classification). This group was divided into two subgroups: I – six dogs receiving oral tamoxifen, and II – six dogs with cyclophosphamide administered orally. The control group included six healthy dogs. The blood was sampled from the saphenous access vein two times at 14-d intervals before the drug administration, three times every 7 d during administration, and two times every 14 d after completion of the therapy. The basic blood tests were carried out and the subpopulations of TCD4+ and TCD8+ lymphocytes, and phagocytic activity of granulocytes and monocytes were determined using flow cytometry. It was found that tamoxifen induced a marked increase in WBC and neutrophil counts, increased phagocytic activity of monocytes, and changed the CD4+:CD8+ ratio (in favour of cytotoxic lymphocyte subpopulation). These findings indicated the stimulation of cell-mediated immunity mechanisms. Cyclophosphamide caused a substantial decrease in the overall leukocyte pool and reduced the percentage of cells activated for phagocytosis, both neutrophils and monocytes even after completion of its administration, which proves its immunosuppressive effects.