Phenotypic and functional heterogeneity of XXXX intestinal intraepithelial lymphocytes defined by cell density: implications for route of differentiation and responsiveness to proliferation induction.

@entity19 @entity5168 @entity1961 @entity26720 @entity3512 @entity3414
The phenotype and function of @entity19 intestinal intraepithelial lymphocytes (IEL) was studied in a Percoll-fractionated preparation that consisted of low-density cells which migrated to the 40-50% Percoll interface (IEL-40), medium-density cells which migrated to the 50-55% interface (IEL-50), and high-density cells which migrated to the 55-70% interface (IEL-55). IEL-40 and IEL-50 cells, the subsets phenotypically most similar to mature IEL, consisted of @entity5168 + T cells that included @entity1961 - CD8+ and @entity1961 + CD8+ cells; @entity1961 + CD8- cells were present only in the IEL-50 fraction. T-cell receptor (TcR)alpha beta and TcR gamma delta cells were present in both IEL-40 and IEL-50 fractions. In contrast, most IEL-55 were @entity5168 -, @entity26720 (HSA)+ cells that were not B cells; some IEL-55 cells were @entity5168 lo HSA- or @entity5168 lo HSA+ suggesting that IEL-55 are immature T cells. TcR alpha beta but not TcR gamma delta was expressed in the IEL-55 fraction. All three IEL fractions consisted of both @entity3414 alpha and @entity3414 beta cells. There was considerable functional heterogeneity between the three IEL fractions such that @entity5168 -induced proliferation was greatest for IEL-50 cells and least for IEL-55 cells; that activity correlated with the proportion of @entity3512 + cells within the fractions. Both IEL-40 and IEL-50 fractions contained activated cytotoxic T lymphocytes (CTL) that were 8-16-fold more lytic than IEL-55 cells. That IEL-55 cells may be precursors of some IEL-40 and IEL-50 cells was demonstrated by a shift in cell density and by an increase in proportions of cells expressing markers of IEL-40 and IEL-50 cells following in vitro stimulation via @entity5168 . The relevance of these findings to differences in functional activities reported for @entity19 IEL is discussed.
