FAS and disease arising from reactivation of latent virus: Although distinct patterns of Bcl-2, CD57, and CD95 co-expression by CFP-10/ESAT-6-specific CD8 T cells were highly sensitive and specific in distinguishing latent infection from active disease, these phenotypic measurements can only be analyzed in individuals who have sufficient numbers of specific CD8 T cells to be detectable in blood ex vivo.