Effects of lactoferrin on the production of interferon-λ by the human intestinal epithelial cell line HT-29

We examined the in-vitro effects of bovine lactoferrin (LF) on the production of interferon-lambda (IFN-lambda), an antiviral cytokine important for the defense of enterocytes, using the human intestinal epithelial cell line HT-29. HT-29 cell cultures were treated with LF for 1 h, and the cultures were stimulated with polyinosinic-polycytidylic acid (poly I: C). LF increased the concentration of IFN-lambda in the culture supernatant after stimulation in a dose-dependent manner. A similar increase in the concentration of IFN-lambda was observed in the supernatant of cells washed between treatment with LF and stimulation with poly I: C. At 6 and 24 h after stimulation with poly I: C (early and late phases, respectively) treated cultures contained significantly higher concentrations of IFN-lambda 1 in the culture supernatant, and significantly higher IFN-lambda 1 and IFN-lambda 2 mRNA levels, than controls. These results suggest that LF activates the innate cellular immunity of the enterocytes to double-stranded RNA and increases the production of IFN-lambda.