Analysis of bovine natural killer cell cytotoxicity following activation by pro-inflammatory cytokines(181.2)

Abstract

Abstract Bovine natural killer (NK) cells are important mediators of the innate immune response to infectious diseases of cattle. Like other mammalian species, bovine NK cells express NKp46 (CD335) and do not express CD3 or a T cell receptor. However, bovine NK cells remain poorly characterized with respect to cytokine activation, in part because the commonly used lymphoma target cell line, K562, apparently fails to induce a significant cytotoxic response by bovine NK cells. We have assessed natural cytotoxicity against a bovine-derived lymphoid cell line (BL3.1) compared to human-derived K562 cells. Lymphocytes activated in vitro with bovine cytokines (IL-2, IL-15, IL-21 and their combination) for different time periods were analyzed for killing activity using these target cells. We observed enhanced killing of BL3.1 cells, suggesting that they are more susceptible to killing by bovine NK cells than K562 cells. Killing activity was detected after 24 hrs of in vitro cytokine stimulation and maximal cytotoxicity was demonstrated following 72-96 hrs of culture with cytokines. Our data indicate that the addition of IL-21 enhances IL-2 mediated cytotoxicity, whereas IL-15 has no effect on NK cytotoxicity for these target cells. Preliminary data suggest that vaccination of cattle with an inactivated foot-and-mouth disease virus (FMDV) vaccine fails to activate NK cells isolated from peripheral blood. Future studies will investigate the ability of FMDV infection to activate bovine NK cells.