CD4 and Ureteral obstruction: Liu et al. (2012) showed massive infiltration by CD4+ T lymphocytes in advanced human immunoglobulin A nephropathy and that depletion of CD4+ T lymphocytes prevented renal fibrosis in UUO (unilateral ureteral obstruction) mice. They also showed that the TH2/TH1 ratio increased progressively after UUO and that TH2-reconstituted mice were more prone to develop renal fibrosis than TH1-reconstituted animals. Likewise, Braga et al. (2012) observed an increase in TH2-related cytokines 7 days after UUO in mice, as well as an accumulation of M2 macrophages in an MyD88 pathway–dependent manner.