text: Increased Foxp3 Protein Expression Is Associated with Low HTLV-I Proviral Load
  Since Foxp3 is expressed almost exclusively within CD4+CD25+ T cells, a major viral reservoir for HTLV-I [33], it was important to determine whether there was an association between Foxp3 and HTLV-I replication in infected patients. We therefore quantitated the Foxp3 protein expression in CD4+CD25+ T cells by flow cytometry and the HTLV-I proviral load (a surrogate marker of viral replication) by real-time PCR from eight patients with HAM/TSP and eight asymptomatic carriers (ACs). The data from this analysis is summarized in Table 1. As expected, patients with HAM/TSP exhibited significantly higher proviral loads (indicated as HTLV-I proviral DNA copies/100 cells) (34.68 +/- 23.19) compared to ACs (4.75 +/- 5.47) (p = 0.0008). The percentage of Foxp3+ cells within the CD4+CD25+ T cell population was significantly greater in ACs (43.23 +/- 12.95) than in HAM/TSP patients (18.59 +/- 5.77) (p = 0.0033). These data suggest that high levels of Foxp3 protein expression are associated with reduced HTLV-I replication in vivo. They also support our recent reports that high proviral loads, which have been shown to correlate with high Tax mRNA in HTLV-I-infected patients, are associated with reduced Foxp3 expression [8,34]. 
  