THP-1 cells as a model for human monocytes

In mammals, circulating monocytes provide effective protection against infection with Gram-negative bacteria. Once challenged with lipopolysaccharide (LPS), a macromolecular structure of the cell wall of Gram-negative bacteria, peripheral monocytes migrate to lymph nodes, differentiate into dendritic cells, and present antigen to CD4⁺ and CD8⁺ T cells with high efficacy, thereby initiating adaptive immunity against Gram-negative bacteria (1). In addition, circulating monocytes have the potential to differentiate into tissue macrophages, thereby contributing to the pool of embryonically derived macrophages and providing help in the phagocytosis of invading pathogens (2).