Abstract

In view of the possible relationship to thrombosis the `anti-heparin' activity of blood protein fractions was studied. Serum and plasma were separated by continuous paper curtain electrophoresis and two different groups of fractions with anti-heparin activity found. One group was associated with the fast γ globulins and the other with the α globulins. The fast γ activity appeared to be identical with the contact activation product (activated factors XI and XII). The α globulin activity is different from any of the known serum clotting factors. This activity may be due to a previously unrecognized clotting factor or may be a coagulant property of certain blood proteins which act by binding heparin.

The clinical implications of these findings are discussed. It is suggested that the fast γ globulin anti-heparin fraction may be identical with Wessler's serum thrombotic accelerator and the α globulin activity is a separate entity.