Impact of T cell activation, HIV replication and hepatitis C virus infection on neutrophil CD64 expression.

BACKGROUND: Overexpression of the Fc receptor CD64 on neutrophils is associated with innate immune response and bacterial infections. During HIV infection a large set of immune disorders including T-lymphocyte over-activation, microbial translocation, impairment of neutrophil functions, and immunodeficiency may interplay with neutrophil CD64 expression. METHODS: Associations of neutrophil CD64 expression with CD8+ T cell activation, CD4+ T cells number, HIV, and HCV replications were investigated in HIV infected patients using a standardized method. RESULTS: Higher neutrophil CD64 expression was observed in HIV infected subjects compared to healthy controls (0.91 vs. 0.75, P < 0.001). Among 115 HIV infected patients, nine (8.8%) had a CD64 expression over the clinical threshold as calculated against bead standard (i.e., 1.5). HIV viremic patients were more likely to have an index above 1.5 (OR: 6.68, P values: 0.01). A trend for correlation between CD64 expression and CD8 T cell activation was observed (P values: 0.08). Blood CD4+ T lymphocyte depletion and HCV replication did not affect neutrophil CD64 expression. CONCLUSIONS: HIV infection and HIV replication are associated with up-regulation of neutrophil CD64. CD64 overexpression above the clinical threshold was observed in a minor proportion of HIV infected individuals treated by antiretroviral therapy and may be a marker of neutrophil activation related to non-AIDS-linked comorbidities. © 2016 International Clinical Cytometry Society.