Unconjugated bilirubin inhibits C1 esterase activity

ARRIAGA SM; BASIGLIO CL; MOTTINO AD; ALMARÁ AM

CLINICAL BIOCHEMISTRY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2009 vol. 42 p. 919 - 921

0009-9120

Objective: To evaluate if unconjugated bilirubin (UB) inhibits C1 esterase activity.             Design and Methods: Esterase activity was evaluated by C1-mediated hydrolysis of N-acetyl-L-tyrosine ethyl ester, and binding of UB to C1r and C1s was assessed by dot-blot analysis.             Results: UB inhibited C1 enzymatic activity. C1r, C1s and human serum albumin bound [14C]-UB to a similar extent.             Conclusions: UB inhibits C1 esterase activity, apparently due to a direct pigment-protein interaction. This could explain the inhibitory action of UB on complement activation.