To further compare the involvement of Siglec-1 and other well-characterized HIV-1 receptors (CD4 and CCR5 molecules) involved in HIV-1 infection, M-CSF–derived MDMs from 3 donors (donors 132, 130, and 202) were evaluated for HIV-1 infectivity (Fig. 5A). The gene discussed is CD4; the disease is HIV-1 infection.