Send to

Choose Destination
AIDS. 1992 Mar;6(3):249-56.

Correlation between kinetics of soluble CD4 interactions with HIV-1-Env-expressing cells and inhibition of syncytia formation: implications for mechanisms of cell fusion and therapy for AIDS.

Author information

Section of Membrane Structure and Function, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.



To study the kinetics of the interactions between soluble (s) CD4 and HIV-1-Env-expressing cells in relation to subsequent events leading to cell fusion and inhibition of syncytia formation.


Vaccinia-HIV-1 (Env)-infected CD4- T-cells were used to study the kinetics of sCD4-gp120/41 interactions and syncytia formation (with CD4+ T-cells) under identical conditions.


sCD4 association and dissociation rates for HIV-1-Env-expressing cells, and quantification of sCD4-induced gp120 shedding was determined by a quantitative flow cytometry assay. Syncytia inhibition was measured in the continuous presence of sCD4, or after washing of HIV-1-Env-expressing cells following pre-incubation with sCD4.


The kinetics of syncytia inhibition correlated with sCD4 binding when sCD4 was maintained during the culture. When Env-expressing cells, which had been pre-incubated with sCD4, were washed to remove unbound sCD4, no syncytia formation inhibition was observed, even following sCD4-induced shedding of greater than 50% of surface gp120 molecules.


The lack of syncytia inhibition seen after removal of unbound sCD4, even after pre-incubation of cells under saturation and gp120 shedding conditions, indicated that sufficient numbers of fusogenic molecules remained on the sCD4-treated cells. In addition, fast dissociation of pre-bound sCD4 occurred in culture. These results are important for understanding HIV-1-Env-mediated cell fusion and AIDS therapy.

[Indexed for MEDLINE]

Supplemental Content

Loading ...
Support Center