Monocyte expression of adhesion molecules in HIV-infected patients: Variations according to disease stage and possible pathogenic role

We used flow cytometry to study the expression of adhesion molecules at the cell surface and actin polymerization of whole-blood monocytes in 35 HIV-i nfected patients at different stages of the disease. Monocytes were activat ed in vivo, as demonstrated by increased expression of the adhesion molecul e CD11b/CD18, reduced L-selectin antigen expression, and increased actin po lymerization. These abnormalities were present in asymptomatic patients wit h CD4+ cell counts greater than 500/mu l and did not increase with disease progression or Viral load. Sialyl-Lewis x and CD31 expression at the monocy te surface was normal in asymptomatic and symptomatic non-AIDS patients. In contrast expression of both molecules was strongly reduced in patients wit h AIDS. This change, despite normal maximal CD11b/CD18 expression and norma l maximal actin polymerization, could contribute to the increased susceptib ility to bacterial infections in AIDS. In contrast enhanced monocyte activa tion may promote their transendothelial migration in non-AIDS patients, pos sibly explaining the macrophage infiltration that can occur early in the di sease.