Interleukin-1 beta levels in human embryo culture supernatants and their predictive value for pregnancy.

Interleukin 1 (IL-1) is possibly one factor produced by the embryo that might have a role in the maternal immunological recognition of pregnancy. The purpose of this study was to identify an embryo-related factor suitable for prediction of pregnancy during IVF procedures. For this purpose, IL-1 beta levels were measured in 21 samples of human embryo culture-conditioned media. The average number of embryos per sample was 5 +/- 1. Simultaneously, 16 cell culture media containing 10% autologous serum but no embryos were tested as controls. IL-1 beta levels were measured using the ELISA technique, and the biological activity of IL-1 was measured by means of a C3H/HeJ mice thymocyte proliferation assay. The average IL-1 beta level +/- S.E.M. was 49 +/- 7 pg/ml in embryo culture-conditioned media and 12 +/- 2 pg/ml in controls (P < 0.001). The average IL-1 beta level in embryo culture-conditioned media from viable pregnancy cycles was 82 +/- 6 pg/ml (n = 8), while in those cases that did not result in viable pregnancies the IL-1 beta level was significantly lower (28 +/- 4 pg/ml, n = 13, P < 0.001). The IL-1 activity of embryo culture-conditioned media, measured by [3H]thymidine incorporation in thymocytes was increased, compared with control media (442 +/- 51 counts/min vs. 337 +/- 13 counts/min, P < 0.05), and the highest values corresponded to media containing those embryos that resulted in pregnancies (589 +/- 41 counts/min, P < 0.01 vs. controls). We conclude that the determination of the levels of this cytokine in embryo culture-conditioned media might be a predictive parameter for pregnancies in patients undergoing IVF-ET.