| Abstract: | In both mammalian and avian systems, thymic nurse cells (TNC) have been shown to harbor a heterogeneous population of T lymphocytes (TNC-L) some of which exhibit a postselectional phenotype. By tranplanting micromanipulated single chicken TNC onto the chorionallantoic membrane (CAM) of major histocompatibility complex (MHC)-disparate embryos, an experimental system which allows for the detection of lymphocytes with graft-vs.-host (GVH) reactivity, we demonstrate here that TNC enclose lymphocytes that can develop into both CD4+ single-positive (sp) and CD8+ sp, T cell receptor (TcR)αβ+, or TcRγδ+ cells. This finding was additionally confirmed by serial transfer of primary expanded alloreactive T cells onto the CAM of secondary hosts. All donor TNC-L expressed MHC class II molecules and the interleukin-2 receptor a chain in primary and secondary GVH reactions. Furthermore, we observed selective accumulation of CD8+ and TcRγδ+ host lymphocytes in the CAM upon the induction of a local GVH reaction, most probably as a consequence of the pathological alteration of the epithelium. |
