NKp46 defines ovine cells that have characteristics corresponding to NK cells
2011
Connelley, Timothy | Storset, Anne K | Pemberton, Alan | MacHugh, Niall | Brown, Jeremy | Lund, Hege | Morrison, Ivan W
Natural killer (NK) cells are well recognized as playing a key role in innate immune defence through cytokine production and cytotoxic activity; additionally recent studies have identified several novel NK cell functions. The ability to study NK cells in the sheep has been restricted due to a lack of specific reagents. We report the generation of a monoclonal antibody specific for ovine NKp46, a receptor which in a number of mammals is expressed exclusively in NK cells. Ovine NKp46⁺ cells represent a population that is distinct from CD4⁺ and γδ⁺ T-cells, B-cells and cells of the monocytic lineage. The NKp46⁺ cells are heterogenous with respect to expression of CD2 and CD8 and most, but not all, express CD16 - characteristics consistent with NK cell populations in other species. We demonstrate that in addition to populations in peripheral blood and secondary lymphoid organs, ovine NKp46⁺ populations are also situated at the mucosal surfaces of the lung, gastro-intestinal tract and non-gravid uterus. Furthermore, we show that purified ovine NKp46⁺ populations cultured in IL-2 and IL-15 have cytotoxic activity that could be enhanced by ligation of NKp46 in re-directed lysis assays. Therefore we conclude that ovine NKp46⁺ cells represent a population that by phenotype, tissue distribution and function correspond to NK cells and that NKp46 is an activating receptor in sheep as in other species.
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