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 CD25(high)CD8(+) cells expressed Foxp3, while the mean percentage of Foxp3(+) cells within CD25(low)CD8(+) cells was 3.66%. The absolute count of Foxp3(+)CD25(high)CD8(+) cells was not significantly different from the absolute count of Foxp3(+)CD25(low)CD8(+) cells. The obtained results indicate that CD8(+) cells with the regulatory phenotype, i.e. Foxp3(+)CD25(high)CD8(+) and Foxp3(+)CD25(low)CD8(+) 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.