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Open Access Research

Thrombomodulin phenotype of a distinct monocyte subtype is an independent prognostic marker for disseminated intravascular coagulation

Sang Mee Hwang12, Ji-Eun Kim12, Kyou-Sup Han12 and Hyun Kyung Kim12*

Author Affiliations

1 Department of Laboratory Medicine, Seoul National University College of Medicine, 101, Daehak-ro Jongno-gu, Seoul 110-744, Republic of Korea

2 Cancer Research Institute, Seoul National University College of Medicine, 101, Daehak-ro Jongno-gu, Seoul 110-744, Republic of Korea

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Critical Care 2011, 15:R113  doi:10.1186/cc10139

Published: 14 April 2011

Abstract

Introduction

Thrombomodulin, which is expressed solely on monocytes, along with tissue factor (TF), takes part in coagulation and inflammation. Circulating blood monocytes can be divided into 3 major subtypes on the basis of their receptor phenotype: classical (CD14brightCD16negative, CMs), inflammatory (CD14brightCD16positive; IMs), and dendritic cell-like (CD14dimCD16positive DMs). Monocyte subtype is strongly regulated, and the balance may influence the clinical outcomes of disseminated intravascular coagulation (DIC). Therefore, we investigated the phenotypic difference in thrombomodulin and TF expression between different monocyte subtypes in coagulopathy severity and prognosis in patients suspected of having DIC.

Methods

In total, 98 patients suspected of having DIC were enrolled. The subtypes of circulating monocytes were identified using CD14 and CD16 and the thrombomodulin and TF expression in each subtype, expressed as mean fluorescence intensity, was measured by flow cytometry. Plasma level of tissue factor was measured by ELISA. In cultures of microbead-selected, CD14-positive peripheral monocytes, lipopolysaccharide (LPS)- or interleukin-10-induced expression profiles were analyzed, using flow cytometry.

Results

The proportion of monocyte subtypes did not significantly differ between the overt and non-overt DIC groups. The IM thrombomodulin expression level was prominent in the overt DIC group and was well correlated with other coagulation markers. Of note, IM thrombomodulin expression was found to be an independent prognostic marker in multivariate Cox regression analysis. In addition, in vitro culture of peripheral monocytes showed that LPS stimulation upregulated thrombomodulin expression and TF expression in distinct populations of monocytes.

Conclusions

These findings suggest that the IM thrombomodulin phenotype is a potential independent prognostic marker for DIC, and that thrombomodulin-induced upregulation of monocytes is a vestige of the physiological defense mechanism against hypercoagulopathy.