Activated dendritic cells and monocytes in HIV immunological nonresponders: HIV-induced interferon-inducible protein-10 correlates with low future CD4+ recovery

Abstract

<i>Objective</i>: To explore monocyte and dendritic cell immune responses, and their association with future CD4⁺ gain in treated HIV patients with suboptimal CD4⁺ recovery.<p>

<p><i>Design</i>: A cross-sectional study of HIV-infected, virally suppressed individuals on antiretroviral therapy for at least 24 months; 41 immunological nonresponders (INRs) (CD4+ cell count <400 cells/μl) and 26 immunological responders (CD4⁺ cell count >600 cells/μl). Ten HIV-infected antiretroviral therapy-naive and 10 HIV-negative healthy persons served as controls. CD4⁺ cell counts were registered after median 2.4 and 4.7 years.<p>

<p><i>Methods</i>: Monocyte, dendritic-cell and T-cell activation and regulatory T cells (Tregs) were analyzed by flow cytometry. In INR and immunological responder subgroups matched on age and nadir CD4⁺ cell count, upregulation of interferon-inducible protein-10 (IP-10) and indoleamine 2,3-dioxygenase in monocytes and dendritic cells and cytokines in cell supernatants were measured <i>in vitro</i> in peripheral blood mononuclear cells stimulated with aldrithiol-2-inactivated HIV-1.<p>

<p><i>Results</i>: The INR group displayed higher spontaneous activation of both monocytes (HLA-DR⁺) and myeloid and plasmacytoid dendritic cells (HLA-DR⁺, CD83⁺ and CD86⁺) compared with immunological responders, and this was associated with increased T-cell activation (CD38⁺HLA-DR⁺), an effector memory T-cell phenotype and activated Tregs. The IP-10 response in monocytes after in-vitro HIV stimulation was negatively associated with prospective CD4⁺ gain. IP-10, indoleamine 2,3-dioxygenase and cytokines levels were comparable between the groups, but inversely correlated with activated Tregs in INRs.<p>

<p><i>Conclusion</i>: HIV-infected individuals with suboptimal immune recovery demonstrated more activated monocytes and in particular dendritic cells, compared with patients with acceptable CD4⁺ gain. A high level of HIV-specific IP-10 expression in monocytes may be predictive of future CD4⁺ recovery.