Although other authors also use IL-2 to detect response in MTB infected subjects [17, 18, 19] we previously showed, for the first time, that out of a number of M. tuberculosis antigens tested including Ala-DH, ESAT6, CFP10, PstS1, HSPX, antigen 85B, only Ala-DH induced IL2 production measured by an ELISPOT assay could clearly distinguish children with LTBI from those with active TB [13]. This evidence concerns the gene IL2 and tuberculosis.