EFFECTS OF TRANSFORMING GROWTH-FACTOR BETA(1) ON RAINBOW-TROUT ONCORHYNCHUS-MYKISS MACROPHAGE RESPIRATORY BURST ACTIVITY

Natural bovine transforming growth factor beta(1) (TGF-P,) was found to have both enhancing and suppressing effects on the respiratory burst activity of rainbow trout, Oncorhynchus mykiss, head kidney macrophages. Incubation with TGF-beta(1) alone increased respiratory burst activity using doses from 0.05 to 0.2 ng/mL. However, incubation of activated macrophages with TGF-beta(1) decreased their respiratory burst activity in a dose-dependent manner. Coincubation of macrophages with activating signals (macrophage activating factor containing supernatants and tumor necrosis factor a) and TGF-beta(1) inhibited the ability of such signals to increase respiratory burst activity. Similarly, pretreatment of macrophages with TGF-beta(1) prior to treatment with activating signals resulted in a time and dose-dependent decrease in activity relative to cells not treated with TGF-beta(1). These suppressive effects were largest using higher doses of TGF-beta(1) (1 ng/mL). The conservation of TGF-beta s and their possible mode of action are discussed.