Mouse fetal thymus lobes cultured in IL-2 generate CD3+, TCR-gamma delta-expressing CD4-/CD8+ and CD4-/CD8- cells.

Whole, undisrupted, 14-day fetal mouse thymus lobes were liquid-cultured in medium supplemented with 10 U/ml rIL-2. The cells that emerged from these fetal thymus lobes grew in an IL-2-dependent manner and showed non-MHC-restricted cytolytic activity. By two-color flow microfluorimetric analysis they could be subdivided into CD4-/CD8+ and CD4-/CD8- subpopulations, both of which contained CD3+ cells. Northern analysis of total cellular RNA revealed full-length transcripts of gamma- and delta-message, predominantly the truncated (1.0 kb) beta- and no detectable alpha-message. Taken together, these results show that by culturing 14-day fetal thymus lobes in IL-2, in the absence of deliberate mitogen stimulation, CD3+, TcR-gamma delta-expressing CD4-/CD8+ and CD4-/CD8- T cells are obtained. Such cells may represent the precursors of similar cells found outside the thymus in adult mice.