RESUMO
Cells bearing the T-cell differentiation alloantigens TL and Thy-1 were enumerated in preparations of spleen and lymph node cells of nu/nu mice. Healthy nu/nu mice had few or no demonstrable TL+ or Thy-1+ cells whereas mice with viral hepatitis, including some born of nu/nu X nu/nu matings, had many. Healthy nu/nu mice were treated daily with the thymic hormone thymopoietin or with ubiquitin, polypeptides that induce the differentiation of TL+Thy-1" cells from TL-Thy-1- precursors in vitro. After 14 days, 20 to 40 percent of their spleen cells were of the TL+Thy-1+ phenotype typical of thymocytes and 10 to 25 percent of their lymph node cells were TL-Thy-1+, typical of later T-cell differentiation. Similar frequencies of such cells were found in untreated nu/nu mice suffering from severe viral hepatitis. These data conform to the current view that prothymocytes are preprogrammed cells whose maturation to thymocytes, normally induced in the thymus by thymopoietin, can be triggered by other agents under abnormal circumstances. Tests of T-cell function were not included in this study.