Bovine natural cell mediated cytotoxicity (NCMC): Activation by cytokines

Abstract

Incubation of bovine peripheral blood mononuclear leukocytes (PBML) with the cytokines (CK) IL-2, α-IFN, γ-IFN or IL-4 resulted in significant increases in natural cell mediated cytotoxicity (NCMC) over endogenous levels, as determined in an 18 h 51Cr-release assay using the human K562 or mouse Yac-1 target cell lines. Endogenous cytotoxic activity of bovine natural effector cells (NEC) using K562 or Yac-1 target cells was minimal (killing <8%). After 18 h of incubation with the CK hu rIL-2, α-bov rIFN, γ-bov rIFN or hu rIL-4, NEC had significant increases in cytotoxic activity for both K562 and Yac-1 target cells. Significant increases in cytotoxic activity were not found after incubation of NEC with IL-1 or β-IFN. Specific killing varied with CK concentration in a dose dependent manner and was proportional to effector: target cell ratio. Activation of the bovine NEC by CK was rapid, occurring within 6–12 h of incubation with α-IFN or γ-IFN and within 12–18 h of incubation with IL-2. Incubation of bovine PBML with IL-2 and α- or γ-IFN or with α-IFN and γ-IFN showed that these CK do not act in a synergistic manner to increase NCMC in the bovine NEC.