Characterization of murine CD160+ CD8+ T lymphocytes

CD160 is an Ig-like glycoprotein expressed on NK, NKT and TCRγδ T cells, as well as intestinal intraepithelial T lymphocytes. In addition, a minor subset of CD8+ but not CD4+ T cells in the periphery is also known to express CD160, but the subset has not been fully characterized. In this study, we prepared anti-murine CD160 mAbs and investigated the expression profile of CD160 on various subsets of CD8+ T cells. The amount of CD160 on almost all CD8+ T cells was increased upon CD3-mediated stimulation in vitro, and soluble CD160 was found to be released. Flow cytometric analysis revealed most CD8+ T cells expressing CD160 to show a CD44high phenotype in vivo. On further analysis, both CD44highCD62Llow effector memory T cells (TEM) and CD44highCD62Lhigh central memory T cells (TCM) expressed CD160 at an intermediate level. High levels were evident with recently activated CD8+ TEM. Naïve CD8+ T cells presumably immediately after stimulation (CD44lowCD62LlowCD69+) also expressed CD160, but only at a low level. Purified CD160+ CD8+ T cells from OT-1 transgenic mice expressing TCR against OVA residues 257–264 presented by H-2Kb produced IFN-γ more rapidly than CD160− CD8+ T cells upon antigen stimulation. These results together show that CD160 is expressed on the majority of CD8+ memory T cells as well as recently activated CD8+ T cells.