BIOLOGICAL PROPERTIES OF A CD4 IMMUNOADHESIN

MOLECULAR fusions of CD4, the receptor for human immunodeficiency virus (HIV; refs 1-4), with immunoglobulin (termed CD4 immunoadhesins) possess both the gpl20-binding and HIV-blocking properties of recombinant soluble CD4, and certain properties of IgG, notably long plasma half-life and Fc receptor binding5,6. Here we show that a CD4 immunoadhesin can mediate antibody-dependent cell-mediated cytotoxicity (ADCC) towards HIV-infected cells, although, unlike natural anti-gpl20 antibodies, it does not allow ADCC towards uninfected CD4-expressing cells that have bound soluble gpl20 to the CD4 on their surface. In addition, CD4 immunoadhesin, like natural IgG molecules, is efficiently transferred across the placenta of a primate. These observations have implications for the therapeutic application of CD4 immunoadhesins, particularly in the area of perinatal transmission of HIV infection. © 1990 Nature Publishing Group.