LACTOFERRIN-MEDIATED PROTECTION OF THE HOST FROM MURINE CYTOMEGALOVIRUS-INFECTION BY A T-CELL-DEPENDENT AUGMENTATION OF NATURAL-KILLER-CELLACTIVITY

The administration of bovine lactoferrin (LF) with 1 mg/g body weight before the murine cytomegalovirus (MCMV) infection completely protecte d the BALB/c mice from death due to the infection. In these LF-treated mice, a significant increase in the activity was found in the NK cell s but not in the cytolytic T lymphocytes which recognized an MCMV-deri ved peptide. Moreover, the elimination of the NK cell activity by an i njection with anti-asialo GM 1 antibody abrogated such augmented resis tance, thus supporting the hypothesis that the LF-mediated antiviral e ffect in vivo is performed through the augmentation of NK cell activit y. No such LF-mediated antiviral effect in vivo with the increased NK cell activity was found in athymic nude mice, whereas it was restored completely by the transfer of splenic T cells from LF-treated donors. These findings therefore suggest that T lymphocytes induce both the au gmentation of NK cell activity and the resultant antiviral effect in t he LF-treated hosts.