Expression of rearranged TCRγ genes in natural killer cells suggests a minor thymus-dependent pathway of lineage commitment

Abstract

Abstract Natural killer (NK) cells are thought to develop from common lymphoid progenitors in the bone marrow. However, immature thymocytes also retain NK potential. Currently, the contribution of the thymus-dependent pathway in normal steady-state NK-cell development is unknown. Here, we show that TCRγ genes are rearranged in approximately 5% of neonatal and 1% of adult mouse splenic NK cells, and similar levels are detected in NK cells from TCRβ,δ double-knockout mice, excluding the possibility of T-cell contamination. NK-cell TCRγ gene rearrangement is thymus dependent because this rearrangement is undetectable in nude mouse NK cells. These results change the current view of NK-cell development and show that a subset of NK cells develops from immature thymocytes that have rearranged TCRγ genes.