Second, previous studies have found that DPP4 expression is decreased in certain periphery T-cell subsets in HT patients compared with healthy CTs, while Wang et al thought that the percentages of CD26/DPP4 expression on Tc1, Tc2, Th1, and Th2 cells were not different between healthy CTs and HT patients (8, 9). The gene discussed is DPP4; the disease is hematocrit.