Uptake of human immunodeficiency virus envelope protein gp120 by human trophoblast in culture.
OBJECTIVE
Our purpose was to determine whether human trophoblast has a cell surface CD4 antigen that will bind to gp120, the envelope protein of human immunodeficiency virus.


METHODS
Uptake of iodine 125-labeled gp120 by trophoblast in culture was measured. Particular attention was paid to technical details that may have caused the contradictory results reported by previous investigators: the source of the recombinant gp120, the method of radioiodination, and the isolation procedure of trophoblast to ensure elimination of contaminating cells, particularly macrophages.


RESULTS
Uptake of transferrin-free iodine 125-labeled gp120 to trophoblast was unaffected by adding a 200 molar excess of gp120, by preincubating gp120 with soluble CD4 to block the CD4 binding sites on gp120 and by preincubation of trophoblast with a blocking antibody to CD4 (OKT4a). In contrast, uptake of gp120 by CD4-positive H9 human lymphocytes was reduced 79% by a 200 molar excess of gp120 and > 50% by a CD4-blocking antibody.


CONCLUSIONS
Uptake of gp120 to trophoblast is by a high capacity, CD4-independent mechanism that is probably nonspecific and may be related to the mechanism for binding other circulating glycoproteins in maternal blood.
Esterman
A L
AL
Department of Pediatrics, New York University Medical Center, NY 10016, USA.
Finlay
T H
TH
Lee
J D
JD
Dancis
J
J
D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D015704:CD4 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D046508:Culture Techniques; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015497:HIV-1; D006801:Humans; D007457:Iodine Radioisotopes; D011247:Pregnancy; D011994:Recombinant Proteins / Q000378:metabolism; D014327:Trophoblasts / Q000276:immunology / Q000378:metabolism*
D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D007457:Iodine Radioisotopes; D011994:Recombinant Proteins