Gestational age correlates with immunosuppressive properties of hydatidiform mole pregnancies

Soluble trophoblast extracts (HME) from some human hydatidiform mole pregnancies suppress IL-2-dependent T-cell proliferation, while others express no immunosuppressive bioactivity. This study was designed to determine if suppression by HME was correlated with gestational age, uterine size, or hCG secretion.

Soluble extracts were prepared from nine hydatidiform mole trophoblast samples and screened for immunosuppressive activity using a murine cytotoxic T-cell proliferation assay (CTLL-2). Gestational ages were determined from last menstrual cycle and uterine size was estimated at the time of surgery. Serum samples were collected prior to uterine evacuation and were assayed for human chorionic gonadotropin (hCG).

Four of nine HME samples significantly (P < 0.05) suppressed CTLL2 proliferation, while five exhibited no suppressive activity. A strong positive correlation (r = 0.639) was noted for the relationship between gestational age of the molar pregnancies and interleukin-2 (IL-2)-stimulated CTLL2 proliferation (expressed as % of control) in the presence of HME (500 micrograms/mL). This indicates that HME suppression of CTLL2 proliferation is highest in early gestation and then declines with increasing gestational age. A similar correlation was observed between estimated uterine size at surgery and CTLL2 proliferation with added HME, although the association was not as strong (r = 0.359). No association was noted between hCG levels and CTLL2 proliferative responses (r = -0.091).

The results of this study suggest that production of immunosuppressive factors by hydatidiform mole trophoblast is developmentally regulated, and decreases with advancing gestation.