RT Journal Article SR Electronic(1) A1 Schols, Dominique A1 Pauwels, Rudi A1 Baba, Masanori A1 Desmyter, Jan A1 De Clercq, ErikYR 1989 T1 Syncytium Formation and Destruction of Bystander CD4+ Cells Cocultured with T Cells Persistently Infected with Human Immunodeficiency Virus as Demonstrated by Flow Cytometry JF Journal of General Virology, VO 70 IS 9 SP 2397 OP 2408 DO https://doi.org/10.1099/0022-1317-70-9-2397 PB Microbiology Society, SN 1465-2099, AB Summary We have developed a flow cytometric method for demonstrating cell fusion between human immunodeficiency virus type 1 (HIV-1)- or HIV-2-infected HUT-78 cells and uninfected CD4-bearing MOLT-4 cells. Syncytium formation due to an interaction between the gp120 glycoprotein expressed on HIV-infected HUT-78 cells and the CD4 receptor present on MOLT-4 cells, resulted in an immediate decrease in the number of MOLT-4 cells; after a 24 h incubation period almost all MOLT-4 cells had disappeared from the culture. To show that the target MOLT-4 cells and not the aggressor HUT-78 cells were destroyed, specific monoclonal antibodies (MAbs) that reacted with antigens expressed on either MOLT-4 or HUT-78 cells were used. The formation of giant cells andthe concomitant disappearance of MOLT-4 cells was blocked by MAbs specific for OKT4A and Leu3a, and, to a much lower level, by the MAbs specific for OKT4 and gp120. MAbs specific for OKT3,Leu2a, HLA-DR, Leu18 and LeuM3 did not prevent the disappearance of MOLT-4 cells. Sera from two AIDS patients containing antibodies to the HIV envelope glycoproteins did not protect MOLT-4cells against the destructive effect of the HIV-infected HUT-78 cells. The fusion index, thepercentage fusion inhibition and the 50% fusion inhibitory concentration of the MAbs can be accurately determined with the flow cytometric assay. The method can be readily implemented to evaluate any therapeutic treatment by examining its capacity to block cell-to-cell fusion, and hence destruction of the target bystander cells. Five anti-HIV compounds which have been previously shown to interfere with HIV binding to cells (namely pentosan polysulphate, heparin, suramin, aurintricarboxylic acid and Evans Blue) were further evaluated by this new method. With the exception of heparin, all of these compounds were found to inhibit cell-to-cell fusion andthe concomitant destruction of the target bystander cells. Azidothymidine failed to inhibit fusion or bystander T cell destruction., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-70-9-2397