FXIII in Fbn clots from FXIII-B(−)+A plasma. FXIII-A (A) and -B (B) in the supernatant separated from the Fbn clot after the cross-linking reaction were quantified by ELISA, and their amounts are given as a percentage of unreacted plasma. The mean ± S.D. (error bars) of 3–5 independent experiments was plotted. Open circle, normal plasma; open square, FXIII-B(−)+A plasma (FXIII-B-depleted plasma supplemented with rFXIII-A); filled square, FXIII-B(−)+A plasma with rFXIII-B. C, cleavage of the activation peptide of FXIII-A during Fbn cross-linking in FXIII-B(-)+A plasma. FXIII-A in the supernatant and Fbn clot was visualized by Western blotting using an anti-FXIII-A antibody. D, effect of FXIII-B on cleavage of the activation peptide of FXIII-A in a reaction with purified Fbg. Purified human Fbg was reacted with thrombin in the presence of rFXIII-A without or with rFXIII-B, and then samples were analyzed by Western blotting using an anti-FXIII-A antibody. *, p < 0.05; **, p < 0.01; ***, p < 0.001.