Bovine natural killer cell subsets can be defined by differential expression of CD161 (KLRB1).

Natural killer (NK) cells play a vital role in the immune response to infection, disease, and vaccination. Bovine NK cell subsets have been described; however, a more in-depth characterization is currently hindered by the lack of species-specific reagents in comparison to humans and mice. CD161, encoded by the KLRB1 gene, is a C-type lectin-like receptor known to be highly expressed in human NK cells. CD161 has been described in human immunity as defining a pro-inflammatory subset of NK cells that are capable of responding to cytokines. The specific function and importance of bovine CD161+ cells have yet to be defined. This study developed and characterized a novel mouse anti-bovine CD161 monoclonal antibody and determined the expression of CD161 on NK cells, CD8 T cells, and gamma delta T (γδT) cells in peripheral blood from calves. Future research will investigate the specific function and targeting of the described CD161+ subsets in baseline immune response, infection, and response to vaccination.