Antibodies against b2-glycoprotein I (b2-GP I) and Their Relationship to Fetoplacental Antigens
 

L. FIALOVÁ, I. MALBOHAN, L. MIKULÍKOVÁ, O. BENEŠOVÁ¹, A. ZWINGER¹
 

First Institute of Medical Chemistry and Biochemistry, Institute of Clinical Chemistry, First Medical Faculty, Charles University, Prague, Czech Republic, ¹Institute of Child and Mother Care, Prague, Czech Republic
 

Received March 16, 2001
Accepted January 22, 2002
 

Summary
Binding of beta₂-GP I to anionic phospholipids is thought to be the major antigen required in the reaction of anticardiolipin antibodies to phospholipids. The aim of this study was to investigate the changes of anti-beta2-GP I IgG during the first and second trimester of pregnancy and the relationship between the levels of anti-beta2-GP I and fetoplacental antigens and the correlation between anti-beta2-GP I IgG and antibodies against oxidized low-density lipoprotein IgG (oLAb) in serum of pregnant women. We determined anticardiolipin antibodies (ACA) IgG and maternal serum levels of alpha₁-fetoprotein (AFP), human chorionic gonadotrophin (HCG) and trophoblast-specific beta1-glycoprotein (SP1) in 204 pregnant women in the first and second trimester. From this group we selected 52 serum samples positive for ACA IgG and 16 samples negative for ACA IgG. In the samples of selected patients, the levels of anti-b2-GP I IgG and oLAb IgG were determined. Anti-b2-GP I IgG levels significantly decreased in the second trimester (6.2±9.3 U/ml, mean ± S.D.) in comparison with the first trimester (8.3±10.4 U/ml) (p=0.05). Multiple of median (MoM) AFP correlated negatively but not significantly in the first trimester with anti-b2-GP I (r = -0.261, p = 0.12). In the second trimester this correlation was significantly negative (r = -0.278, p = 0.04). The Spearman correlation coefficients for MoM HCG and anti-beta2-GP I were 0.158 for the first trimester and 0.174 for the second trimester. MoM SP1 also did not correlate significantly with anti-beta2-GP I in both trimesters. The correlation between anti-beta2-GP I IgG and oLAb IgG was not significant (r = -0.06). In the first trimester 40 % serum samples were positive for anti-b2-GP I IgG and negative for oLAb IgG or vice versa, while 60 % samples in the second trimester were positive only for one determined autoantibody. We can conclude that the levels of anti-beta2-GP I IgG decrease during the second trimester probably as the result of the effects of some immunosuppressive agents associated with pregnancy. The finding of negative correlation between AFP and anti-b2-GP I suggests that anti-b2-GP I has an influence on fetus development.

 

Key words
Anti-beta2-glycoprotein I · Antiphospholipid antibodies · alpha1-fetoprotein · Human chorionic gonadotrophin · Trophoblast-specific - beta1-glycoprotein · Pregnancy

Reprint requests
L. Fialová, First Institute of Medical Chemistry, Kateřinská 32, 121 08 Prague 2, Czech Republic. E-mail: lFial@lf1.cuni.cz
 

ISSN 0862 - 8408