Background: Circulating interferon-γ (IFN-γ) concentration may be sustained at a high level regardless of the initiation of antiretroviral therapy (ART) in some patients with HIV-1 infection. In the present study, we examined the clinical characteristics of HIV-1-infected patients with high levels of plasma IFN-γ.
Methods: The study subjects were patients infected with HIV-1 who were either naïve to ART with CD4+ cell count > 200 cells/μL (n = 12), or had achieved viral suppression after ART for over a year (n = 188). The levels of plasma IFN-γ and interleukin-6 (IL-6) were measured by the enzyme-linked immunosorbent assay. Patients were divided into high IFN-γ and low IFN-γ groups based on a cutoff level of 5 pg/mL.
Results: The high IFN-γ group included 41 patients (21%). Compared to the patients on ART with low IFN-γ levels, those on ART in the high IFN-γ group were more likely to be younger than 50 years of age (P = 0.0051) and less likely to have dyslipidemia (P = 0.0476) or to be on a protease inhibitor (P = 0.0449). There was no significant difference between groups in the median increase of CD4+ cell counts from the initiation of ART for up to 3 years. However, after 4 years, the increase in CD4+ cell counts was significantly lower in the high IFN-γ group compared with that in the low IFN-γ group. There were no such significant differences between patients with low and high (> 2 pg/mL) levels of plasma IL-6.
Conclusion: We concluded that HIV-1-infected patients with high levels of circulating IFN-γ did not have a higher rate of comorbidities related to immune activation. However, they exhibited lower CD4+ cell count recovery after 4 years of being on ART. This deficit could be a consequence of persistent immune activation.
Keywords: CD4+ cell count recovery; HIV-1 infection; Interferon-γ; Interleukin-6.