A novel biological effect of platelet factor 4 (PF4): enhancement of LPS-induced tissue factor activity in monocytes

CS Engstad, K Lia, Ø Rekdal, JO Olsen… - Journal of Leucocyte …, 1995 - academic.oup.com
CS Engstad, K Lia, Ø Rekdal, JO Olsen, B Østeoid
Journal of Leucocyte Biology, 1995academic.oup.com
In a previous study we have shown that granulocytes enhance lipopolysaccharide (LPS)-
induced tissue factor (TF) activity in monocytes in a platelet-dependent reaction. The present
investigation was undertaken to examine the role of a platelet activation product, platelet
factor 4 (PF4), in LPS-induced TF activity in monocytes. Platelet lysate supernatant, purified
PF4, and the COOH-terminal tridecapeptide of PF4, termed PF4 (58–70), enhanced LPS-
induced TF activity in monocytes of whole blood dose dependently. A monoclonal antibody …
Abstract
In a previous study we have shown that granulocytes enhance lipopolysaccharide (LPS)-induced tissue factor (TF) activity in monocytes in a platelet-dependent reaction. The present investigation was undertaken to examine the role of a platelet activation product, platelet factor 4 (PF4), in LPS-induced TF activity in monocytes. Platelet lysate supernatant, purified PF4, and the COOH-terminal tridecapeptide of PF4, termed PF4(58–70), enhanced LPS-induced TF activity in monocytes of whole blood dose dependently. A monoclonal antibody against P-selectin eliminated the enhancing effect of PF4(58–70) on LPS-induced TF activity in monocytes, and PF4(58–70) was shown to act synergistically with tumor necrosis factor α (TNF-α). However, PF4(58–70) did not enhance TNF-α secretion in LPS-stimulated whole blood. The major effect of PF4(58–70) was granulocyte dependent. Our results suggest that PF4 might play an important role in LPS-stimulated monocyte TF activity of whole blood.
Oxford University Press