Recombinant beta-galactosidase fusion proteins from Mycobacterium tuberculosis were purified by affinity chromatography and used for stimulation of unselected T lymphocytes freshly isolated from healthy individuals. It was found that the 12-kDa, 19-kDa, 65-kDa and 71-kDa recombinant (r) proteins tested stimulated T cells from healthy individuals in an antigen-specific way. These data demonstrate that it is feasible to screen purified r-proteins with unselected T cell populations. The existence of T cells with reactivity to these antigens in healthy individuals suggests T cell activation independent from clinical disease and hence that these proteins are not indicative for active tuberculosis.