CD27 and tuberculosis: The median percentage ESAT6-specific IFNγ secreting total lymphocytes was 0.12% versus 0.09% (P = 0.65), 1.54% versus 1.07% (P = 0.35) for CD4+ T lymphocytes, and 1.17% versus 2.3% (P = 0.81) for CD27− CD4+ memory T lymphocytes for the active TB and non-active TB groups, respectively.