Impairment of Polymorphonuclear Neutrophil Function in HIV-Infected Patients

Abstract

Impaired polymorphonuclear neutrophil (PMN) function may contribute to the onset of certain bacterial and fungal infections and to tissue damage in human immunodeficiency virus (HIV)-infected patients. Published data on PMN function in HIV infection are controversial, possibly because most studies have involved PMNs isolated from the normal blood environment by various procedures that may modify PMN responses. We therefore used flow cytometry to study the expression of adhesion molecules at the PMN surface, actin polymerization, and the oxidative burst of whole-blood PMNs in 42 HIV-infected patients at different stages of the disease. These PMNs were activated in vivo, as shown by increased expression of the adhesion molecule CD11b/CD18, reduced L-selectin antigen expression, increased actin polymerization, and increased H₂O₂ production. The alterations were present in asymptomatic patients with CD4⁺ cell counts above 500/μl and did not increase with progression of the disease. This PMN activation could contribute to the oxidative stress described in HIV infection. Stimulation by bacterial N-formyl peptides showed dysregulation of L-selectin shedding and decreased H₂O₂ production after ex vivo priming with tumor necrosis factor-α or interleukin-8. These latter impairments, which correlated with the decrease in CD4⁺ lymphocyte numbers, could contribute to the increased susceptibility of HIV-infected patients to bacterial infections.