Follicular fluid α1-antitrypsin—correlation with fertilizing capacity of oocytes

Summary. Follicular fluid and serum concentrations of α-antitrypsin (α₁-AT) were determined by radial immunodiffusion in 72 samples obtained from 33 infertile women undergoing in-vitro fertilization and embryo transfer. A statistically significantly lower concentration of α₁-AT was found in follicular fluids from which mature oocytes were recovered (mean 1.52, SE 0.06 g/l) than in those yielding immature oocytes (mean 2·96, SE 0·22 g/l). There was also a significantly higher rate of fertilization (85%) for oocytes from follicular fluids with α₁-AT concentrations of ≤2·0 g/l than for those obtained when the α₁-AT concentration was >2·0 g/l (only 25%). The mean follicular fluid α₁-AT concentration (1 ·52, SE 0·06 g/l) of follicles yielding mature oocytes was significantly lower than the relevant mean serum concentration (3·17, SE 0·10 g/l). There was, however, no significant difference between follicular and serum concentration of α₁-AT in the group yielding immature oocytes or in the serum concentrations between the different oocyte maturity groups. The measurement of follicular α₁-AT may be a useful adjunct in predicting which oocytes are mature and likely to be fertilized.