Mh. Wagner et al., Complement and contact activation related to surfactant response in respiratory distress syndrome, PEDIAT RES, 45(1), 1999, pp. 14-18
The activation of inflammation and coagulation cascades is part of the path
ogenesis of adult respiratory distress syndrome (RDS). Previous studies hav
e demonstrated contact activation in preterm infants with RDS, whereas no c
oncordant results have been found with complement activation. In this study
, both systems were investigated in preterm infants with severe RDS and rel
ated to surfactant response. Thirty preterm newborns with severe respirator
y distress (Fio(2) > 0.5), but with no evidence of infection or fetal acido
sis, were studied. Eighteen healthy preterm newborns of similar gestational
age and birth weight served as controls. The study; group was divided into
two subgroups, according to their response to a porcine natural surfactant
6 h after administration: responders (Fio(2) reduction > 50%) and poor res
ponders (Fio(2) reduction less than or equal to 50%). Clq, C4, factor B, C3
a, C5a, complement, and CI-inhibitor activity, as well as factor XIIa, were
determined in blood samples, drawn 24 h after birth. Except for C1-inhibit
or concentration and C1-inhibitor activity, all parameters for infants with
severe RDS were different from controls. Complement precursor proteins wer
e lower, and activated split products of the complement and contact system
were higher. Infants with a poor response after application of surfactant s
howed higher amounts of C3a, C5a, and factor XIIa but lower Clq and C4 leve
ls compared with infants with a good response to surfactant. Activation of
the complement and the contact system was demonstrated in all respiratory d
istress patients. This activation was more pronounced in poor responders to
exogenous surfactant.