CD274 and tuberculosis: There was variation between patients, reflected by spread in MFI of PD-L1 expression (Fig. 2A), likely representing the heterogeneity of TB patients, extent of disease and the natural variability in the human immune response to Mtb. However, overall expression of PD-L1 on whole blood leucocytes from patients with active TB was significantly increased compared with blood leucocytes from healthy controls (Fig. 2A; Supporting Information Fig. 1A), in line with the microarray findings.