Activation of macrophages by lactoferrin: Secretion of TNF-α, IL-8 and NO

Abstract

When macrophages were cultured with lactoferrin, cytokines such as tumor necrosis factor (TNF-α), interleukin 8 (IL-8) and nitric oxide (NO) were secreted. Secretion of TNF-α peaked at 6 h of incubation in the presence of lactoferrin and then declined. About 80% of the maximum secretion of IL-8 was observed at 6 h of incubation. The concentration of IL-8 in the culture medium remained almost constant between 24-72 h. In contrast, no siginificant effect on NO secretion was observed at 6 h, but a significant effect was observed at 24 h and secretion gradually increased between 24-72 h. The effects of lactoferrin on the secretion of TNF-α, IL-8 and NO were dose-dependent and lactoferrin had a significant effect on secretion at concentrations greater than 10 mg/ml. The use of reverse transcription-polymerase chain reaction (RT-PCR) showed that the results obtained were consistant with the cytokine secretion results. It is concluded that lactoferrin activates macrophages which result in the secretion of TNF-α, IL-8 and NO.