HIV-1 infects and alters immune function of a monocyte subset expressing low CD14 surface phenotype

Monocytes represent a leukocyte subset that express high levels of CD14 on their surface (CD14-high), These cells play a critical role in the pathogen esis of HIV-1 infection. In the present study, we have identified a monocyt e subset expressing an extremely low level of CD14 (CD14-low), and examined their susceptibility to HIV-1 infection. Phenotypic analysis by flow cytom etry of these cells revealed a low level of CD4, but the absence of CD3, CD 14, CD19, and CD83 surface markers. Both CD14-low and CD14-high cell popula tions expressed CD13 and CD33 markers on their surface, suggesting these ce lls to be of myeloid origin, Morphologically, CD14-low cells were indisting uishable from CD14-high cells. CD14-low cells were susceptible to infection with a monocytotropic strain of HIV-1 (HIVADA) However, like CD14-high mon ocytes, CD14-low cells could not be productively infected with a T cell tro pic strain of HIV-1 (H9/HTLVIIIB) Similar to CD14-high monocytes, CD14-low cells were capable of inducing antigen-stimulated CD4(+) T-cell proliferati on. HIV-1 infection substantially reduced their ability to induce antigen-s timulated T-cell proliferation. These data indicate that CD14-low cells bel ong to the monocyte lineage and may play an important role in the immunopat hogenesis of HIV-1 infection.