Memory phenotype of antigen-specific CD4⁺IFN-γ ⁺ T cells in HHC and TB patients. Box and Whisker plots show range, inter-quartile range, and median of antigen-specific IFN-γ-secreting memory T cell subsets in HHC and TB patients. Effector memory subset secretes more IFN-γ than other memory subsets in HHC and TB patients. The difference between HHC and TB was calculated by Mann-Whitney test. EM-Effector memory T cell; CM: Central Memory T cell; TM: terminally differentiated memory T cell; TB: tuberculosis patients; HHCs: healthy household contacts.