CD4 and congenital rubella syndrome: However, the frequency of effector CD4+ T cells in the spleen, which are higher in mice subjected to CRS was decreased when mice received adoptive transfer of Treg cells (control 20.7 ± 3.7 vs. CRS 34.4 ± 4.2 vs. CRS + Treg cells 28.3 ± 4.2% of CD4 + CD44hi; Cohen’s d size effect of 3.5 between control and CRS and 1.44 between CRS and CRS + Treg cells) (Figure 2E).