Similar to the observations in mice, human CD19+CD24hiIgDlo/−CD38lo and CD19+CD24hiIgDlo/−CD38hi Bregs were also found to express a higher level of PPARδ than human CD19+CD24loIgDhi mature B cells (Fig. 5a), and frequencies of both Breg subsets were increased in cancer patients compared to healthy subjects (Fig. 5b). Here, PPARD is linked to cancer.