RECEPTOR-MEDIATED MATERNOFETAL TRANSFER OF IMMUNOGLOBULINS - INHIBITION OF TRANSPORT OF ANTI-HIV-1 IMMUNOGLOBULIN BY GENERIC IMMUNOGLOBULINS IN THE IN-VITRO PERFUSED PLACENTA

Objectives: The passage of immunoglobulin G (IgG) across the placenta is thought to involve Fc' receptors on the syncytiotrophoblast. To con firm the receptor dependency of this process we have studied the chang es in the tissue content and transfer kinetics of immunoglobulins and hyperimmune serum to HIV (HIVIG) during in vitro dual placental perfus ion. Methods: Isolated lobules of term placentae from normal pregnanci es were perfused in a model of maternal and fetal circulation. The per fused tissue was compared to fresh tissue samples from the same placen ta for the content of IgG, Ige subclasses, IgM, cytokeratin, human pla cental lactogen and SP1 antigen by immunohistochemistry and by protein elution. Results: The immunoglobulin staining faded by an average of 40% during the Ist hour of perfusion. In contrast, staining for cytoke ratin, human placental lactogen and SP1 remained unchanged. During a 4 -hour recycling of endogenous immunoglobulins in the maternal circulat ion, IgG and HIVIG crossed to the fetal side in a steady I ate. The tr ansport of HIVIG could be inhibited by preperfusion with an intravenou s gammaglobulin preparation (IVIG). Discussion: The transfer of IgG ac ross the placenta occurs in a steady state rate consistent with a rece ptor-mediated mechanism. Furthermore, inhibition of HIVIG maternofetal transfer by IVIG further establishes the receptor-mediated transfer o f immunoglobulins through the placenta.