CXCL10 and infection: Without known exposure to recent TB infection, QFT-positives in the HC group were most likely a result of remote infection, while those in the HHC group probably had recent infection due to close contact with smear-positive pulmonary TB patients, and those QFT-positives with elevated level of baseline IP-10 may suggest a higher risk to develop ATB, for the recent finding showed that IP-10 level increased when exposed household contacts developed to active TB [9].