Quantitative study of EPF activity along temporal dimensions (duration) due to surgical abortion further promotes the efficiency to take EPF activity and its rate of change as truly index for monitoring embryonic care and development of normal pregnancy.

Early pregnancy factor (EPF), an immunosuppressive substance, appears in mammalian maternal serum at a very early stage after fertilization. To investigate the normal distribution of EPF in the human body, the rosette inhibition test has been used to detect EPF in human amniotic fluid. The mean value of rosette inhibition titer (RIT) was significantly higher (5.93 +/- 0.43 SE) in 52 amniotic fluid samples (16-30 weeks' gestation) than in 23 nonpregnant sera (3.54 +/- 0.11), indicating that something in amniotic fluid inhibits rosette formation. This inhibitory factor is recognized as EPF or EPF-like substance for its activity significantly correlated with that of EPF in serum from the same donor (r = 0.756: P less than 10(-6]. The immunological significance of the EPF-like substance in amniotic fluid may be important to the survival of semiallogeneic conceptus.

PROBLEM: To detect whether or not the early pregnancy factor (EPF)‐like activity, or chaperonin 10, could be in the sera of patients with trophoblastic tumor in order to find another more efficient means to diagnose this kind of tumor. METHOD OF STUDY: The rosette inhibition assay was used to detect EPF‐like activity in 216 sera, collected from patients with gestational trophoblastic tumor, including 47 sera of patients with choriocarcinoma, 68 sera of patients bearing invasive mole, and 101 sera of patients with vesicular mole. RESULTS: The accuracy of diagnosing malignant trophoblastic tumor by detecting EPF‐like activity is 91.3% (105/115), with a false positive rate of 14.58% and a false negative rate of 4.48% by this method. Furthermore, the rosette inhibition titer (RIT) values have significant difference (P < 0.001) between the sera in patients with malignant trophoblastic tumor before treatment and those after treatment. CONCLUSIONS: This study demonstrated that diagnosis of malignant trophoblastic tumor could be made with an accuracy of 91.3%) by detecting EPF‐like activity and that EPF‐like activity could be used as an indicator to distinguish benign from malignant trophoblastic tumor.