Bovine lactoferrin (LF) was supplemented with Cu at three contents of 0.16, 0.32, and 0.64 mg/g LF, respectively. After then, LF and Cu-supplemented LF products were assessed for immuno-modulation in murine splenocytes and RAW264.7 macrophages, using dose levels of 10-40 μg/mL and four evaluation reflectors including stimulation index of splenocytes, T lymphocyte subpopulations, macrophage phagocytosis, and cytokine secretion. The results indicated that LF and Cu-supplemented LF products had suppression on splenocytes as well as concanavalin A (ConA)- or lipopolysaccharide-stimulated splenocytes; however, using lower Cu-supplementation content (i.e., 0.16 mg/g LF) and lower dose level (10 μg/mL) alleviated this suppression significantly (P < 0.05). Compared to LF, Cu-supplemented LF product of lower Cu-supplementation content at lower dose level yielded slightly enhanced macrophage stimulation, increased CD4/CD8 ratio of T lymphocyte subpopulations in ConA-stimulated splenocytes, and significant secretion enhancement for interleukin-2 (IL-2), IL-4, interferon-γ (in splenocytes), IL-1β, and tumor necrosis factor-α (in macrophages) (P < 0.05). Furthermore, Cu-supplemented LF product of higher Cu-supplementation content (i.e., 0.64 mg/g LF) at higher dose level mostly showed opposite effects in the cells, in comparison with its counterpart at lower dose level. It is concluded that Cu-supplementation of LF can alleviate or increase LF's effects on the two immune cells, and moreover, Cu content of supplemented LF is a key factor that modulates these effects.
