Immunofluorescent localization of antithrombin III in human skin.

The presence in clinically normal human skin of the proteinase inhibitor antithrombin III (ATIII) has been studied by indirect immunofluorescence (IF) microscopy. The IF staining reaction for ATIII in skin tissue sections was most prominent in vessel wall structures. The simultaneous use of fluorescent staining techniques for nuclear DNA revealed that ATIII antigen tends to be concentrated at the level of the vascular endothelial basement membrane, in contrast to the typical intra-endothelial distribution of Factor VIII related antigen. Although our findings indicate that ATIII is normally associated with dermal vessel walls, it remains to be seen whether its presence there is of importance, e.g. in modulating inflammatory skin responses.