Foxp3 Expression in Bovine CD8+ T Cells Is Associated with the Intensity of CD25 Expression

The aim of the undertaken research was to determine whether Foxp3+CD25+CD8+ cells exist in cattle and whether Foxp3 expression in CD8+ T cells is correlated with the intensity of CD25 expression. It has been found that 0.66 and 2.36% of CD8+ cells on average showed high and low expression of the CD25 molecule, respectively. On average, 11.61% of CD25highCD8+ cells expressed Foxp3, while the mean percentage of Foxp3+ cells within CD25lowCD8+ cells was 3.66%. The absolute count of Foxp3+CD25highCD8+ cells was not significantly different from the absolute count of Foxp3+CD25lowCD8+ cells. The obtained results indicate that CD8+ cells with the regulatory phenotype, i.e. Foxp3+CD25highCD8+ and Foxp3+CD25lowCD8+ cells, occur naturally in bovine peripheral blood, although both of these subpopulations are relatively small. There is a positive correlation between the intensity of CD25 expression and the expression of the transcription Foxp3 factor in bovine CD8+ cells.