CA-125 secretion by luteal phase endometrium in vitro

The source of CA-125 in normal women and the mechanisms which control CA-125 production remain to be defined. This study was initiated to examine the pattern of secretion of CA-125 from luteal phase endometrium. Endometrial samples were obtained during the early luteal phase (histological days 16-18) and late luteal phase (histological days 25-27) from ovulatory women with a laparoscopically normal pelvis. The tissue was maintained in explant culture using Trowell's T-8 medium with either no additions (NA), progesterone (P), oestradiol (E2), or E2 + P. The concentration of CA-125 in spent media from the second day in culture was determined by immunoradiometric assay. In early luteal endometrium, the concentration of CA-125 in spent media from the NA treated wells was significantly higher than when the endometrium was exposed to either P or E2 + P. Similar differences were noted between treatments for the late luteal endometrium. Within each treatment, there was a higher concentration of CA-125 in the spent media from the late versus the early luteal endometrium. We conclude that the endometrium is a potential source of serum CA-125 and that endometrial CA-125 is suppressed by P in both the early and the late luteal phase. Further, there appears to be an increase in endometrial CA-125 secretion from the early to the late luteal phase.