IFN-, but not IP-10, MCP-2 or IL-2 response to RD1 selected peptides associates to active tuberculosis.

Summary Objectives: To evaluate whether in vitro response to Mycobacterium tuberculosis RD1 peptides selected by computational analysis, measured by IFN-g, IP-10, MCP-2 or IL-2 production, is associated with active tuberculosis (TB) in a country with a high incidence of TB. Methods: 129 individuals were prospectively enrolled, 41 with active-pulmonary TB and 88 without (household contacts and community controls). A whole blood assay based on RD1 selected peptides was performed. Soluble factors were evaluated by ELISA in plasma harvested at day1-post-culture. Enrolled individuals were also tested by QuantiFERON TB-Gold In tube (QFT-IT) and tuberculin skin tests (TST). Results: IFN-g response to RD1 selected peptides was significantly higher in active TB patients than in household contacts and community controls. IP-10 and MCP-2 response did not differ between active TB patients and household contacts, although it was higher in these groups compared to community controls; conversely IL-2 response did not differ among the three groups. When IFN-g response to RD1 selected peptides was scored based on receiver-operator- characteristic analysis, active TB was predicted with 68% sensitivity and 86% specificity