Activated CD8 T cells acquire NK1.1 expression and preferentially locate in the liver in mice after allogeneic hematopoietic cell transplantation

Immune cells expressing both NK and T cell markers include CD1d-dependent NKT cells and CD1d-independent NKT-like cells. We now describe the presence of NK1.1+CD8+ T cells in the liver, but not other tissues (spleen, bone marrow, thymus or peripheral blood) in mice receiving allogeneic hematopoietic cell transplantation (allo-HCT). These cells are CD1d-independent TCRαβ+ T cells with an effector/memory CD44hiCD62L− phenotype, and do not express Ly49 receptors. Furthermore, these cells were derived from donor splenocytes, but not bone marrow cells. Depletion of CD8+, but not NK1.1+, cells from donor splenocytes prior to transplantation prevented the generation of NK1.1+CD8+ T cells, indicating that these cells arose from donor NK1.1−CD8+ splenic T cells. These results provide direct evidence that donor CD8+ T cells can acquire NK1.1 expression upon activation in allo-HCT recipients and that these NK1.1+CD8+ NKT-like cells maintain an effector/memory phenotype and persist in the recipients with preferential localization in the liver.

► CD1d-independent NKT-like cells are rare in normal naïve mice and predominantly reside in spleen and bone marrow. ► This study demonstrates conversion of donor CD8 T cells into NKT-like cells upon activation in allogeneic recipients. ► These NK1.1+CD8+ donor cells are long lived, express an effector/memory phenotype and preferentially reside in the recipient liver.