Differentiation of monocytes in vitro: Influence of different types of substances

The monocyte is one of the cell types activated in inflammatory processes to leave the blood and to enter the site of tissue inflammation through the endothelium as part of the cellular infiltrate. In tissue, monocytes differentiate to macrophages. This process is characterized by the expression of differentiation antigens, which can be monitored by monoclonal antibodies. A set of monoclonal antibodies has been used to design a test to analyse the ability of substances to influence the pattern of antigen expression during macrophage differentiation. Irritant substances stimulate the enhanced expression of an 'acute marker', which indicates the infiltration of macrophages into acutely inflamed tissues. Anti-inflammatory substances stimulate the enhanced expression of a 'middle marker' associated with the down-regulatory phase of macrophages. The stimulation of the 'acute marker' is positively correlated with the potential of substances and products to induce or elicit adverse skin reactions.