CTLA4 and parasitic infectious disease: On the other hand, among the asymptomatic malaria group, levels of CD4+PD-1+ and CD4+PD-1+CD57+ could predict and explain some of the variation observed in parasitemia (p < 0.05; p < 0.0001) whereas for CD8+ T cells, the expression of CTLA-4 (p < 0.001) and PD-1+CTLA-4+ (p < 0.0001) were good predictors of parasitemia (Figure S3; Table S2).