Factor XIII is not involved in human platelet-collagen interaction.

A role of factor XIII (FXIII) on the interaction of human platelets with collagen was investigated using either formaldehyde fixed-washed platelets (FWP) or nonfixed platelets. The adhesion of FWP to bovine type I collagen was measured by using either an aggregometer or a collagen immobilized glass beads column. The interaction of non-fixed human platelets with collagen was measured with in vitro bleeding time (Thrombostat-4,000), which was performed by passing citrated whole blood through the filter covered with rat type I collagen under the constant shear stress. FWP adhesion to the collagen immobilized column (1,300 micrograms collagen) was not changed by the addition of commercial FXIII preparation (Fibrogammin); the adhesion was 42.7% in the presence of 1% human serum albumin, 42-43% in the presence of 1-2 U/ml of FXIII. The addition of rabbit antibody to FXIII to normal FWP did not change the degree of adhesion; 42.3% (1:100 anti-FXIII) and 46.1% (normal rabbit serum). Furthermore, platelets from the patient with congenital FXIII deficiency normally aggregated by bovine collagen and the adhesion of the patient FWP to the collagen was similar to that of normal FWP. Prolongation of partial thromboplastin time and the changes of thromboelastograph of normal plasma were observed after mixing with the collagen, and factor VIII, FXIII and von Willebrand factor were adsorbed by the collagen. The amount of FXIII in normal human plasma bound to collagen was 17, 23 and 54% at the concentration of the collagen 250, 500 and 1,000 micrograms/ml, respectively. The binding of plasma ristocetin cofactor was not different between normal control and the patient with FXIII deficiency. These data suggest that FXIII is not involved in human platelet interaction with the type I collagen, while FXIII in normal human plasma binds to the collagen.