The Contact Activation System (CAS) in cord blood: Measurement of CAS components and comparison with mother's blood. A pilot study

- The FXII, FXI and PK in the cord blood of full-term fetuses were similar to those observed in mother's blood.
- HMWK was lower in the fetuses as compared to the mother's blood.
- New reference values need to be determined for CAS factors in newborns.

IntroductionClassical reference data concerning the coagulation system and fibrinolysis in fetuses and newborns date back to the 1990s. Since that time a number of methodological or other improvements have been implemented, which may cast some doubt on timeliness of the data. The study objective was to measure the levels of Contact Activation System (CAS) components by antigen, i.e. factors XII and XI (FXII, FXI), prekallikrein (PK) and high molecular weight kininogen (HMWK) in cord blood and maternal blood.Material and methodsThe study group consisted of 35 healthy parturient women with an uneventful pregnancy and birth. The samples of cord blood and maternal blood were obtained immediately after delivery, before clumping the umbilical cord. The CAS components were measured by immunoenzymatic method (ELISA).ResultsThe median concentrations of CAS components in cord blood plasma and mother's plasma were as follow: FXII: 1.02 (0.60- 2.58) ng/mg protein vs. 0.94 (0.66-1.86) ng/mg protein (p > 0.05); FXI: 2.71(0.03-8.0) ng/mg protein vs. 0.92 (0.03-10.44) ng/mg protein (p > 0.05); PK: 168.78 (104.28-261.16) pg/mg protein vs. 113.44 (79.94-146.70) pg/mg protein (p > 0.05); HMWK: 2169.45 (1530.64- 2539.83) ng/mg protein vs. 2857.96 (2541.52-3161.04) ng/mg protein (p < 0.001).Conclusions1. The antigen levels of the three contact factors, i.e. FXII, FXI and PK in the cord blood of full-term and healthy fetuses were similar to those observed in mother's blood immediately after delivery. Only high molecular weight kininogen was found to be lower (accounting for 84% of the values noted in mothers). 2. Based on our measurements, we claim that the cited reference data concerning the contact factors in full-term and healthy newborns are underestimated; hence, new reference values need to be determined for each antigen and activity contact factor level.