To identify a Tr1 cell gene signature in an experimental malaria model that would allow future functional testing of candidate signature molecules in vivo, we infected triple reporter (Il10gfp × Ifngyfp × foxp3rfp) C57BL/6 mice with PbA and then isolated Th0 (CD4+GFP–YFP–RFP–), Th1 (CD4+GFP–YFP+RFP–), and Tr1 (CD4+GFP+YFP+RFP–) cells from the spleens by cell sorting at day 5 p.i. Due to their low numbers, we were unable to obtain sufficient numbers of IL-10–single positive cells (CD4+GFP+YFP–RFP–) for further analysis (Figure 3A). The gene discussed is CD4; the disease is malaria.