AUGMENTATION OF NATURAL-KILLER-CELL ACTIVITY IN MICE BY ORAL-ADMINISTRATION OF TRANSFORMING-GROWTH-FACTOR-BETA

The latent form of transforming growth factor-beta (TGF-beta) in human milk and platelets was converted to the active form when conscious, p ylorus-ligated mice were given human milk and platelets by intragastri c intubation. Oral administration of TGF-beta exerted enhancing effect s on the natural killer (NK)-cell activities in spleen and liver. Augm entation of NK-cell activities in spleen was observed for 7 days after oral administration of TGF-beta. TGF-beta at concentrations of 5 and 20 ng produced the greatest augmentation of NK-cell activities in sple en. However, NK-cell activities in spleen were unaffected when TGF-bet a was given intravenously. Interleukin (IL)-12 production in spleen wa s enhanced by oral administration of TGF-beta, but not by intravenous administration of TGF-beta. These findings suggest that large amounts of TGF-beta in human milk are involved in early antiviral protection t hrough the augmentation of NK-cell activities.