Demonstration of the in vitro Antiviral Properties of Bovine Lymphokine-Activated Killer (LAK) Cells

In cattle, cells with functional characteristics similar to those of natural killer (NK) cells are difficult to detect. However, lymphokine-activated killer (LAK) cells can be detected readily after in vitro activation of peripheral blood mononuclear leukocytes (PBML) with interleukin-2 (IL-2). In the present study, we demonstrated that IL-2–activated PBML preferentially lyse bovine herpesvirus type 1 (BHV-l)-infected cells and that the cell responsible for the lysis copurified with the cell responsible for lysis of K562. The IL-2–activated effector cells were capable of significant reducing virus production. The reduction in virus yield seemed to be by an interferon (IFN)-independent mechanism, as the amount of IFN induced in effector cells by BHV-1 was not altered by the addition of IL-2. Furthermore, enrichment of cytotoxic cells by passage through nylon wool columns removed the capability of PBML to produce IFN in response to the virus. These results suggest that activation of LAK mechanisms in cattle plays a role in controlling virus spread.