The expression of another well-characterized HDF, purine-rich element binding protein α (Pur-α) was reported to be significantly lower in monocytes than in MDDCs, which is assumed to contribute to the lower susceptibility to HIV-1 infection in monocytes (Gallia et al., 1999; Wortman et al., 2000). The gene discussed is PURA; the disease is HIV-1 infection.