Antigenic and functional levels of alpha-1-antitrypsin in serum during normal and diabetic pregnancy

Objectives: Serum alpha-1-antitrypsin (AAT) concentration may not be representative of the functional capacity of this inhibitor. The aim of this study was to determine the antigenic and functional serum levels of AAT during normal and diabetic pregnancy. Methods: Serum AAT concentration was measured on NOR-Partigen plates (Dade Behring). Trypsin inhibitory capacity (TIC) in the serum was determined with N-benzoyl-DL-arginine-p-nitroaniline (BAPNA, Sigma) as substrate. The examined material included pregnant women with type 1 diabetes mellitus (n = 16) studied prospectively in successive. stages of pregnancy, healthy pregnant women in the first trimester (n = 12), second trimester (n = 15), third trimester (n = 15) and healthy non-pregnant women (n = 14). Results: Serum concentration of AAT in all consecutive phases of diabetic pregnancy is higher as compared to normal pregnancy (P < 0.0001). Serum TIC is significantly lower in the first and third trimesters in diabetic pregnancy (P < 0.05, 0.001, respectively). Specific activity of serum AAT (mg of trypsin inhibited by 1 mg of AAT) does not change between subsequent trimesters both in normal and diabetic pregnancy and in diabetic pregnancy is two times lower as compared to normal pregnancy. Conclusion: In spite of the higher level of AAT in the serum in diabetic pregnancy, the ability of this inhibitor to inhibit trypsin is two times lower as compared to normal pregnancy. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.