Andersen and colleagues found that a protein fraction obtained from M. tuberculosis was immunologically active in mice, suggesting that it was one of the proteins recognized by T cells. In this paper the authors identified and purified the active protein, ESAT-6, and showed that it consists of 95 amino acids. This work and that of Mahairas and colleagues (No. 11995) led to a new test called the Interferon gamma release assay.

(Thanks to Ron Cox for this reference and its interpretation.)