EX-VIVO HUMAN PLACENTAL-TRANSFER OF HUMAN IMMUNODEFICIENCY VIRUS-1 P24 ANTIGEN

OBJECTIVE: Our purpose was to determine whether human immunodeficiency virus-1 p24 antigen crosses the human placenta and, if so, to determi ne its clearance index relative to antipyrine. STUDY DESIGN: Eight ter m human placentas from uncomplicated vaginal or cesarean section deliv eries were studied by ex vivo placental perfusion to determine the inc idence and concentration required to obtain passage of p24 antigen int o the fetal circulation. The concentration of p24 antigen was determin ed by antigen-capture enzyme immunoassay. RESULTS: The passage of p24 antigen into the fetal circulation was observed in three of five place ntas studied when the p24 antigen concentration in the maternal circul ation was 2942.8 +/- 401 pg/ml. When the p24 concentration in the mate rnal circulation was raised approximately fourfold to 14506 +/- 4124 p g/ml, p24 antigen passed to the fetal circulation in two of three plac entas and in three of three placentas in the closed perfusion system. CONCLUSIONS: p24 antigen crossed the human placenta to the fetal circu lation in what appears to be a concentration-dependent manner.