Degradation of human plasma fibrin stabilizing factor XIII subunits by human granulocytic proteinases.

Decreased activity of fibrin stabilizing factor XIII may occur in diseases with enhanced destruction of granulocytes. Haemorrhage and impaired wound healing may result. It has been shown by means of SDS-polyacrylamide gel electrophoresis that the neutral proteinases from human polymorphonuclear granulocytes, the Elastase Like Proteinase (ELP), and the Chymotrypsin Like Proteinase (CLP), are able to digest purified human plasma factor XIII. Both subunits, a and b, are affected at concentrations which might locally or systemically occur under pathophysiological conditions. Higher concentrations are required for the degradation of subunit b. Depending on the proteinases, the concentration used and the time of incubation, numerous split products were formed. To obtain comparable effects, the concentration of CLP had to be about twice that of ELP. Aprotinin had only a slight inhibitory effect on the two leukocyte proteinases. The results presented indicate that factor XIII is degraded and inactivated by granulocytic proteinases, both subunits being altered by these proteinases. Therefore the determination of subunit b may be helpful in differentiating between the proteolytic effect of thrombin which degrades only subunit a, and the granulocyte proteinases.