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Updated: Jul 13, 2026

Flow Cytometry Analysis of Tissue Factor Expression in Human Platelets
Published on: November 22, 2024
M protein from Streptococcus pyogenes induces tissue factor expression and pro-coagulant activity in human monocytes
Lisa I Påhlman1, Erik Malmström1, Matthias Mörgelin1
1Department of Clinical Sciences, Lund, Section for Clinical and Experimental Infection Medicine, Lund University, SE-22184 Lund, Sweden.
Abstract:
Invasive infections caused by the important pathogen Streptococcus pyogenes are often associated with disturbed blood coagulation in the human host, and may in severe cases develop into the life-threatening condition disseminated intravascular coagulation. In this study, the addition of M1 protein to human blood or purified peripheral blood mononuclear cells led to a dose-dependent increase of pro-coagulant activity, which was mediated by an upregulation of tissue factor on monocytes. Analysis of the resulting clots by transmission electron microscopy revealed that the cells were covered with a fibrin network that seemed to originate from the cell surface. Taken together, the results imply an important role for M proteins in the induction of haemostatic disorders in invasive streptococcal infectious diseases.
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