EMIGRATION OF SELECTED SUBSETS OF GAMMA-DELTA-CELLS FROM THE ADULT MURINE THYMUS( T)

Cells bearing the gammadelta form of the TCR make up only 1 - 3% of T cells in the adult murine thymus and peripheral lymphoid organs. Evide nce from studies of nude mice suggests that the development of at leas t some gammadelta T cells is thymus dependent; however, until now it h as not been directly demonstrated that gammadelta cells are exported f rom the thymus. In this paper we have used the technique of labelling thymocytes in vivo with FITC, followed by flow cytometric analysis to trace cells emigrating from the thymus to the spleen. Using this appro ach we have been able to demonstrate for the first time that gammadelt a T cells are exported from the adult murine thymus to the spleen. We also demonstrate that the cells emigrating to the spleen are a selecte d subset of gammadelta thymocytes being heat stable antigen positive, Thy-1+, and expressing low levels of CD44 (Pgp-1). In addition, invest igation of TCR V(gamma) gene usage among adult gammadelta+ thymocytes, recent emigrants, and spleen cells, indicated a selective emigration of gammadelta cells expressing certain V(gamma) genes.