In infected PD-1-deficient mice, we observed a significant increase in IFN-γ production in CD4+ and CD8+ T cells, and higher T-bet expression in CD4+ T cells but not in CD8+ T cells, suggesting the existence of IFN-γ driving transcriptional program independent of T-bet during schistosomiasis. The gene discussed is PDCD1; the disease is schistosomiasis.