Recombinant human lactoferrin modulates human PBMC derived macrophage responses to BCG and LPS

Lactoferrin, an iron-binding glycoprotein found in mammalian mucosal secretions and granules of neutrophils, possesses several immune modulatory properties. Published reports indicate that lactoferrin enhances the efficacy of the tuberculosis vaccine, BCG (Bacillus Calmette Guerin), both by increasing macrophage and dendritic cell ability to stimulate receptive T cells and by modulating the inflammatory response. This report is the first to demonstrate the effects of a recombinant human lactoferrin (10 μg/mL) on human PBMC derived CD14⁺ and CD16⁺ macrophages stimulated with a strong (LPS, 10 ng/mL) or weaker (BCG, MOI 1:1) stimulator of inflammation. After 3 days culture, LPS and human lactoferrin treated CD14⁺ cells significantly increased production of IL-10, IL-6, and MCP-1 compared to the LPS only group. In contrast, similarly treated CD16⁺ macrophages increased production of IL-12p40 and IL-10 and decreased TNF-α. Limited changes were observed in BCG stimulated CD14⁺ and CD16⁺ macrophages with and without lactoferrin. Analysis of surface expression of antigen presentation and co-stimulatory molecules demonstrated that CD14⁺ macrophages, when stimulated with BCG or LPS and cultured with lactoferrin, increased expression of CD86. CD16⁺ macrophages treated with lactoferrin showed a similar trend of increase in CD86 expression, but only when stimulated with BCG.