Fragment Bb: evidence for activation of the alternative pathway of the complement system in pregnant women with acute pyelonephritis.
OBJECTIVE
Pyelonephritis during pregnancy is associated with a more severe course than in the non-pregnant state. This has been attributed to an increased susceptibility of pregnant women to microbial products. The complement system is part of innate immunity and its alternative pathway is activated mainly by microorganisms. The purpose of this study was to determine if activation of the alternative pathway of the complement system (determined by maternal fragment Bb concentrations) occurs in pregnant women with acute pyelonephritis.


METHODS
This cross-sectional study included the following groups: (1) normal pregnant women (n=62) and (2) pregnant women with pyelonephritis (n=38). Maternal plasma fragment Bb concentrations were determined by ELISA. Non-parametric statistics were used for analyses.


RESULTS
(1) Pregnant women with pyelonephritis had a higher median plasma concentration of fragment Bb than those with a normal pregnancy (1.3 μg/ml, IQR: 1.1-1.9 vs. 0.8 μg/ml, IQR: 0.7-0.9; p<0.001); (2) No significant differences were observed in the median maternal plasma concentration of fragment Bb between pregnant women with pyelonephritis who had a positive blood culture and those with a negative blood culture (1.4 μg/ml, IQR: 1.1-3.5 vs. 1.3 μg/ml, IQR: 1.1-1.9; p=0.2).


CONCLUSIONS
Pregnant women with acute pyelonephritis have evidence of activation of the alternative pathway of the complement system, regardless of the presence or absence of a positive blood culture.
Soto
Eleazar
E
Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, USA.
Romero
Roberto
R
Vaisbuch
Edi
E
Erez
Offer
O
Mazaki-Tovi
Shali
S
Kusanovic
Juan Pedro
JP
Dong
Zhong
Z
Chaiworapongsa
Tinnakorn
T
Yeo
Lami
L
Mittal
Pooja
P
Hassan
Sonia S
SS
D000328:Adult; D011415:Complement Factor B / Q000032:analysis / Q000276:immunology*; D003170:Complement Pathway, Alternative / Q000276:immunology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood / Q000276:immunology*; D011704:Pyelonephritis / Q000097:blood / Q000150:complications / Q000276:immunology*; D055815:Young Adult
D011415:Complement Factor B