A smaller percentage of PPD- and RD1-peptide-specific CD4+ cells expressed CD127 in active tuberculosis compared with latent tuberculosis infection, for example, a lower percentage of PPD-specific CD4+ IFN-γ-only- and TNF-α-only-secreting cells expressed CD127 in active tuberculosis compared with latent tuberculosis infection (P < .001 and P = .003, respectively; Figure 3B). Here, CD4 is linked to tuberculosis.