Speculation on the lineage relationships among CD4(-)8(+) gut-derived T cells and their role(s)

The thymus-independent T lymphopoietic capacity of the murine intestinal mu cosa has been established. Cryptopatches have now been identified as the lo cation of the elusive precursors for gut-derived T cells. These cryptopatch cells have been shown to give rise to intestinal T cells expressing either TCR gamma delta or TCR alpha beta. Here we discuss the role of MHC in the development and selection of gut-derived T cells. Through the analysis of i IEL selection in animals expressing a transgenic TCR alpha beta, in the pre sence or absence of p56(lck), we discuss lineage relationships among CD4(-) 8(+) iIEL subsets, and their possible function(s).