Modulation of human monocyte chemotaxis and procoagulant activity by human C-reactive protein (CRP)

Experiments were performed to determine whether the acute phase reactant C reactive protein (CRP) influences the chemotactic and procoagulant activity (PCA) of human peripheral blood monocytes (MO). The results show that concentrations of CRP between 2.5 and 10 ug/ml increased MO chemotaxis approximately 3-fold in a serum free assay system. By contrast 25 and 50 ug/ml CRP did not result in MO chemotaxis. In other experiments MO preincubated for 18 hours with 50 ug/ml CRP demonstrated increased PCA compared to MO preincubated in medium alone. MO preincubated with CRP also displayed an additive increase in PCA when subsequently exposed to low concentrations of lipopolysaccharide (LPS) or immune complexes. However, CRP did not increase the PCA of MO exposed to high concentrations of LPS or immune complexes, which triggered greater PCA. These data suggest that CRP may modulate these early host responses to inflammatory stimuli.