Characterization of subpopulations of T-Cell receptor intermediate (TCRint)T cells

CD1-autoreactive T cells of two types have been demonstrated among T cells expressing the T-cell receptor (TCR) alpha beta at intermediate levels (TCR int cells). One type constitutes a major fraction of the natural killer (NK )1.1(+) TCRint population in C57BL/6 (B6) mice and carries a restricted TCR composed of an alpha-chain with an invariant V alpha 14-J281 rearrangement , and a beta-chain using V beta 8.2, 7 or 2. The second type utilises a var iety of TCR and was derived from CD4(+) cells in mice lacking MHC class II. To increase our understanding of the two different CD1-reactive subsets, w e have investigated and compared the populations of origin: NK1.1(+) and NK 1.1(-) TCRint subsets from MHC class II-deficient mice and CD4(+)NK1.1(+) T cells from B6 mice. The three TCRint populations shared a phenotype indica ting previous activation. and contained low frequencies of cells expressing NK receptors of the Ly49 family. In contrast to control CD4(+) cells, the three TCRint subsets produced high amounts of interleukin (TL)-4 and interf eron (IFN)-gamma after activation. Importantly, no IL-10 could be detected in either TCRint population, implying a distinct function for these cells, different from those of conventional CD8(+) and CD4(+) cells, including the typical T-helper 2 (Th2) cell. Analysis of TCR expression indicated that t he proportion of cells using the semi-invariant V alpha 14/V beta 8.2-type TCR was lower in NK1.1+ cells from MHC class II-negative mice than in CD4()NK1.1(+) B6 cells. Further, usage of the V alpha 14-J281 rearrangement was also demonstrated among NK1.1(-) TCRint cells.