CD8-ALPHA-BETA(-ALPHA-BETA(INTERMEDIATE) LYMPHOCYTES EXPRESSING SKEWED TCRV-BETA REPERTOIRE IN THE LIVER OF AGED ATHYMIC NU() TCR)NU MICE/

Principally, TCR alpha beta cells differentiate and mature in the thym us. However, evidence has accumulated to suggest that some TCR alpha b eta cells develop extrathymically. Such cells have been identified in athymic nu/nu mice that are devoid of a functional thymus. They appear relatively late in ontogeny and randomly increase in number as a func tion of age. Recently, the liver has been suggested as a candidate sit e for thymus-independent development of T cells. Here we show that CD8 alpha beta(+) T cells that express TCR alpha beta at intermediate int ensity (TCR alpha beta(int)) are preferentially localized in the liver of nu/nu mice. This population encompassed cells expressing lectin ce ll adhesion molecule-1 and/or IL-2R beta and cells lacking either of t hese surface molecules. The CD8 alpha beta(+) TCR alpha beta(int) live r lymphocytes in nu/nu mice also differed in their LFA-1 expression ma rginally, whereas in C57BL/6 mice all CD8 alpha beta(+) TCR alpha beta (int) liver lymphocytes expressed LFA-1 at low intensity. Although the TCRV beta repertoire markedly differed among individual animals, the CD8 alpha beta+ TCR alpha beta(int) liver lymphocytes in nu/nu mice pr eferentially used TCRV beta 5 and/or TCRV beta 8. These findings show that CD8 alpha beta(+) TCR alpha beta(int) cells develop in the liver of nu/nu mice and that they arise randomly.