Expression of the thymus leukemia antigen by activated peripheral T lymphocytes.

Peripheral T lymphocytes activated in vitro with concanavalin A (Con A) or alloantigens express the thymus leukemia (TL) alloantigen as assessed by staining with the monoclonal antibody TL.m3 and flow cytometric analysis. The determinants detected by TL.m3 on activated cells are encoded within the Tla region and are detected as early as 48 h after activation with Con A. Several long-term cloned cytotoxic T lymphocyte lines were also examined and each expressed TL. By two-dimensional analysis, the TL isolated from activated peripheral cells was indistinguishable from that found on thymocytes and the leukemia cell line ASL-1.