In human chorionic villi, a numerous macrophages, so-called Hofbauer cells, are located adjacent to trophoblasts. The present study was designed to determine the roles of macrophages on the differentiation of CT and secretion of human chorionic gonadotropin (hCG) and human placental lactogen (hPL).

Macrophages were isolated from the first trimester chorionic villi. They were cultured at 4 x 10⁶/well concentration in serum free medium (SFM) for 48 h, and supernatant was collected. Peritoneal macrophages were also collected and cultured in SFM for 48 h. CT were isolated from the first trimester chorionic villi, plated at 1 x 10⁶/well, and cultured in SFM, medium containing 10% fetal calf serum (FCS), culture supernatant of peritoneal macrophages (PMS), and that of villous macrophages (VMS), respectively. Aggregates of CT were calculated in time course, and stained immunocytochemically with hCG antibody. Supernatant was collected in time course to measure hCG by enzyme immunoassay and hPL by radioimmunoassay.

Aggregates of CT were larger in size and appeared syncytial in PMS than in FCS when cultured for 96 h, but few aggregations were shown in SFM. Numbers of aggregates from 1000 CT were greater at 24 h in PMS (50.6 ± 2; n=5) than in FCS (29 ± 1.8; n=5). hCG and hPL were time-dependently increased and peaked significantly at 96 h in PMS (hCG: 2078.5 ± 13 ng/ml, and hPL: 3.781 ± 0.9 g/ml; n=4), VMS (hCG: 1,1379 ± 145 ng/ml, and hPL: 5.923 ± 1 g/ml; n=4), in comparison with FCS containing media (hCG: 1037.2 ± 14 ng/ml, and hPL: 1.586 ± 0.5 g/ml; n=4).