HIV-1 binding/entry and replication are increased in DCIR-expressing stable transfectants. (A) Raji-CD4 cells were infected with either a retroviral control vector (left) or a retroviral vector encoding for human DCIR (right). Forty-eight hours after transduction, cells expressing high levels of DCIR were isolated by flow cytometry based on eGFP expression. Surface expression of DCIR was monitored by flow cytometry using a combination of PE-labeled anti-DCIR antibody (dotted lines) and a control isotype-matched Ab (continuous lines). Data shown correspond to a single experiment representative of 3 independent experiments. (B) Raji-CD4 and Raji-CD4-DCIR cells were exposed to NL4-3 for 60 minutes. After 3 washes with PBS to remove nonadsorbed virus, cell-associated virus (attached and internalized) was quantified by measuring the p24 content. Data shown correspond to the means ± SD of triplicate samples from 3 independent experiments. (C) Raji-CD4 and Raji-CD4-DCIR were exposed to NL4-3 for 2 hours. After 3 washes with PBS to remove excess virus, cells were maintained in culture for up to 9 days. Cell-free culture supernatants were collected at the indicated time points and assayed for the p24 content. Data shown correspond to the means ± SD of triplicate samples from 3 independent experiments. The statistical significance of differences between Raji-CD4 and Raji-CD4-DCIR is denoted by asterisks: *P < .05. D.P.I. indicates days postinfection.