Effect of preactivation with thrombin on FXIII cross-linking rates.

Cross-linking rates of plasma samples from a subject homozygous for FXIII 34Leu (circles), FXIII 34Val (triangles), a heterozygous subject (squares), and pooled normal plasma (stars) were analyzed in a pentylamine-incorporation assay. FXIII 34Leu cross-linking activity was higher than that of FXIII 34Val, with intermediate response from heterozygous FXIII and pooled normal plasma (A), but this difference was abolished by preactivation with thrombin (B).