PRF1 and dengue disease: Based on the tSNE maps of patients with grade 0, 1, and 2 dengue, we observed the presence of a cluster of NK cells with high intensity of expression of perforin and granzyme B in grade 1 patients, which appears diminished in both grade 0 and grade 2 patients (Figure 2L–N), in line with data shown in Figure 2C–H.