Human monocyte CD163 expression inversely correlates with soluble CD163 plasma levels

Abstract

The inverse relation between monocyte surface CD163 expression and sCD163 levels in human blood suggests that plasma sCD163 is derived from circulating monocytes, in addition to an unknown component from tissue macrophages. The lack of correlation with the absolute monocyte number suggests that such a balance is driven by the functional state of monocytes, rather than simply by numerical changes in circulating cells. We propose that further clinical evaluations of CD163 as a diagnostic parameter should include simultaneous measurements of soluble and cell-bound forms of this antigen.