Summary
Disseminated intravascular coagulation (DIC) may lead to severe thrombotic or hemorrhagic
complications. The present work was undertaken to study the effect of interleukin
6 (IL-6) on variations of key coagulation and fibrinolytic parameters in plasma in
a baboon model of experimental DIC induced by injection of factor Xa and phospholipids
at dosages leading to partial (48%) or complete fibrinogen depletion. Transient increases
of D-dimer, fibrinopeptide A, thrombin-antithrombin and the activated partial thromboplastin
time were observed. Each parameter had a particular (time and Xa/phospho- lipid dose
dependent) pattern of changes. The principal effect of IL-6 was a more rapid restoration
of fibrinogen concentrations and of overall coagulation tests. Injection of factor
Xa/phospholipids led also to a rapid increase of tissue-type plasminogen activator
(t-PA) the extent of which was dependent on Xa/phospholipid dose. Pretreatment with
IL-6 induced a threefold increase of basal t-PA and a corresponding increase of the
t-PA response. Plasminogen activator inhibitor type 1 (PAI-1) concentrations did not
change after low dose Xa/phospholipids, but increased eightfold after high dose Xa/phospholipids.
IL-6 pretreatment induced within 8 h a twentyfold increase of PAI-1 but no further
increase was observed after injection of factor Xa/phospholipids.
Thus, in vivo thrombin generation leads to dynamic modifications of the coagulation
and fibrinolytic systems. The principal effect of IL-6 is a more rapid normalization
of overall coagulation tests, due to normalization of fibrinogen, and an increased
t-PA release response which is partially counteracted by increased PAI-1 concentrations.