MEASUREMENT OF HUMAN EMBRYO-DERIVED PLATELET-ACTIVATING FACTOR (PAF) USING A QUANTITATIVE BIOASSAY OF PLATELET-AGGREGATION

A quantitative bioassay was used to measure the concentration of platelet activating factor (PAF) in medium in which human embryos produced by IVF had been cultured and in various other biological fluids. Following extraction and partial purification, 121 of 228 (53%) media samples in which single human embryos were cultured for 24 h had PAF levels greater than found in corresponding control media. This was assigned as embryo-derived PAF and the corresponding embryos termed 'PAF-positive'. Medium from those PAF-positive embryos transferred to patients who achieved an ongoing pregnancy had a mean PAF concentration of 295 ± 107 nM (mean ± SEM, n > 55), which was significantly greater (P < 0.03) than media of PAF-positive embryos transferred to patients who failed to become pregnant (75 ± 27 nM, n > 66, t-test). The embryos with the faster cleavage rates tended to secrete more PAF (P < 0.01). Although a greater proportion of culture media derived from embryos transferred to patients who achieved a pregnancy were PAF-positive (66 out of 121, 54.5%) compared with those transferred to patients who failed to achieve a pregnancy (55 out of 121, 45.4%), this was not significant (P < 0.05). It was observed that 13% of women who achieved a pregnancy had embryos transferred which did not produce significant amounts of PAF in vitro. This occurred in 26% of women not achieving pregnancy. PAF was detected in only 7% of culture media conditioned by presyngamal fertilized oocytes and was not found in culture medium from unfertilized oocytes, follicular fluid, spermatozoa, seminal plasma, urine from women in early pregnancy or in culture media conditioned by human chorionic villus. Therefore, while there was a significant association between the amount of PAF secreted by embryos and the establishment of pregnancy, the association was not absolute. © 1990 Oxford University Press.