The process of HIV-1 entry in different T-lymphoid cells is enhanced by virus-bound cellular MHC-II glycoproteins. Molt-4 clone 8, Sup-T1, and We17/10 were incubated with similar amounts of virus preparations, standardized in terms of infectivity (TCID50 ), produced by either RAJI-CD4 (▪) or RM3-CD4 (□) cells. Next, cells were washed several times with PBS and treated with trypsin to remove uninternalized viruses. Cells were washed and lysed using Triton X-100, and the amounts of internalized viral p24 were determined using a p24 enzymatic assay. Results shown represent the mean ± SD of triplicate samples. Experiments were repeated three times and gave reproducible results. Asterisks indicate significant differences from infection with virions produced by RM3-CD4 cells at P < .05. Levels of viral p24 in mock-infected cells were less than 20 pg/mL.
