Extravasal fibrin deposition is frequently observed within and around tumorous tissues
and has been implicated in various aspects of tumor growth. However, no adequate information
has been available on the mechanism how intratumoral interstitial fibrin deposits
escape a prompt elimination by the fibrinolytic system. In this study we provide immunomorphological
evidence showing that fibrin deposits in lymph nodes with Hodgkin's disease are stabilized
and made resistant to fibrinolysis by factor XIII (FXIII) of blood coagulation. By
double immuno- fluorescent labelling systems fibrin deposits were simultaneously stained
for α2-antiplasmin (α2-AP), the main physiological inhibitor of fibrinolysis and in a number of nodular
areas they were also labelled for plasmin (ogen). The detection of α2-antiplasmin-plasmin complex-neoantigen (α2-AP-P-Neo) revealed that α2-AP reacted with plasmin, i.e., α2-AP covalently linked to fibrin indeed inhibited intratumoral fibrinolysis. In addition
to fibrin deposits FXIII was also found in cellular elements characterized earlier
as tumor associated macrophages. These cells were attached to fibrin strands suggesting
that they are involved in the intratumoral fibrin formation and might be a source
of fibrin stabilizing factor in the tumor stroma.
Keywords
Intratumoral fibrin formation - Factor XIII - α
2-antiplasmin - Tumor associated macrophages
