[Different localization of thrombomodulin].

Thrombomodulin (TM) is the endothelial cofactor of the anticoagulant protein C system. The distribution of TM in the organism was studied in the rabbit using a goat anti TM, affinity-purified antibody and a peroxidase-labelled antigoat immunoglobulin. TM antigen was found on the endothelial surface of all blood vessels: capillaries, arteries and veins. The reaction was specific: connective tissue, smooth and striated muscle bone, cartilage, nerve tissue, secretary epithelia and all parenchyma studied were not strained. Moreover TM antigen was present on the surface of serosa: peritoneum, pericardium and pleura as well as on synovial membranes and on arachnoid, all along the central nervous system. It was absent from pia and dura mater. The antigen was found only after formalin fixation on the vessels and body cavities surface on which it lies. This observation shows that the antigen is easily detached from these surfaces and suggest a possible mobility of this endothelial molecule for which it lies. This observation shows that the antigen is easily detached from these surfaces and suggest a possible mobility of this endothelial molecule for which production and function sites might differ.