Serum Levels of Complement Factors C1q, Bb, and H in Normal Pregnancy and Severe Pre-Eclampsia

Abstract

BACKGROUND This study aimed to determine the diagnostic role of serum levels of complement C1q, Bb, and H in nonpregnant women, women with normal pregnancy, and women with severe pre-eclampsia. MATERIAL AND METHODS Healthy nonpregnant women (n=30), women with early, middle, and late normal pregnancy (n=30, respectively), and women with severe pre-eclampsia (n=73) were studied. The pre-eclampsia study group included early-onset cases (n=43) and late-onset cases (n=30). Serum levels of Bb were determined by enzyme-linked immunosorbent assay (ELISA), and C1q and H were tested by a turbidimetric immunoassay method. RESULTS In the pre-eclampsia study group, compared with women with normal pregnancy, serum levels of C1q remained stable throughout pregnancy, and Bb levels declined from mid-pregnancy (p=0.250). Serum levels of factor H increased in the middle and late stages of pregnancy, and C1q and H were lower in early-onset severe pre-eclampsia (p<0.001, p=0.009, respectively) and late-onset severe pre-eclampsia (p<0.001, p=0.031, respectively) compared with the early-onset control and late-onset control groups. Serum levels of Bb increased in early-onset severe pre-eclampsia (p=0.001) and late-onset severe pre-eclampsia (p=0.003) compared with early-onset control and late-onset control groups. The area under the receiver operator curve (ROC) for serum C1q, Bb, and H for the diagnosis of early-onset severe pre-eclampsia were 0.814 (95% CI, 0.712-0.917), 0.743 (95% CI, 0.638-0.859), and 0.681(95% CI, 0.556-0.806), and late-onset severe pre-eclampsia were 0.805 (95% CI, 0.694-0.913), 0.796 (95% CI, 0.680-0.911), and 0.662 (95% CI, 0.524-0.800). CONCLUSIONS The classical and alternative pathways of complement were activated in patients with severe pre-eclampsia. Serum levels of C1q, Bb, and H should be studied further as potential diagnostic markers for severe pre-eclampsia.

Figure 1

Complement factor levels of normal nonpregnant women and normal pregnant women. (A) Serum levels of C1q. (B) Serum levels of Bb. (C) Serum levels of complement factor H. Serum levels of (A) C1q, (B) Bb, and (C) H were analyzed in healthy nonpregnant women (n=30), normal pregnant women at early pregnancy (n=30), middle pregnancy (n=30), and late pregnancy (n=30).

Figure 2

Complement factor levels of early-onset and late-onset severe pre-eclampsia (SPE) groups and the control groups for early-onset (EC) and late-onset (LC) group SPE. (A) Serum levels of C1q. (B) Serum levels of Bb. (C) Serum levels of complement factor H. Serum levels of (A) C1q, (B) Bb, and (C) H were analyzed in patients with early-onset severe pre-eclampsia (n=43) and the early-onset control group (n=30), patients with late-onset severe pre-eclampsia patients (n=30) and the late-onset control group (n=30). SPE – severe pre-eclampsia; EC – control group for early-onset SPE; LC – control group for late-onset severe pre-eclampsia.