Although no differences in the percentages of natural regulatory T cell (CD4+CD25+Foxp3+) populations were observed between infection groups in either the spleen or MLN (data not shown), co-infection significantly increased the percentage of IL-4-producing CD4+ and CD8+ splenocytes in comparison to M. bovis BCG-only infected controls (Figure 5B). Here, FOXP3 is linked to infection.