PPD- and RD1-peptide-specific CD4+ cell effector functional subsets were principally TCM in latent tuberculosis infection compared to TEM in active tuberculosis, for example, fewer PPD-specific CD4+ IFN-γ-only secreting cells were TCM in active tuberculosis compared with latent tuberculosis infection (P = .005; Figure 2B). Here, CD4 is linked to tuberculosis.