To evaluate whether the HIV-1-exposed MDM subsets exhibited differences in their ability to transfer HIV-1, Siglec-1hiCD4+MDM from the three donors that were exposed to BaL were cocultured for 3 days with uninfected Siglec-1LoCD4−MDM that were labeled with PKH-67 to distinguish them from Siglec-1hiCD4+MDM or from Siglec-1hiCD4+MDM that may have down-regulated Siglec-1 and CD4 during infection. This evidence concerns the gene CD4 and infection.