IL10 and infection: Using knock-out models for IL-12 or IL-10, the group of Tammy Kielian showed that the presence of IL-12 was required for the recruitment of MDSCs to the site of infection (85), but that the immune suppressive action of MDSCs was mediated by release of IL-10, a cytokine known to shift macrophage polarization toward an anti-inflammatory phenotype (87).