Serum Interleukin-6 and Interleukin-10 levels in people living with HIV on short-term and long-term antiretroviral therapy: a comparative cross-sectional study with HIV-negative controls

Background Antiretroviral therapy (ART) suppresses HIV replication and partially restores immune function, but immune recovery is often incomplete. Interleukin-6 (IL-6) and Interleukin-10 (IL-10) reflect opposing sides of the immune response, pro-inflammatory and regulatory, respectively. They may provide insight into the degree of residual immune dysregulation in people living with HIV (PLHIV) on treatment. This study aims to determine serum IL-6 and IL-10 levels in PLHIV on ART compared to HIV-negative controls. Methods A comparative cross-sectional study was conducted at the HIV Care and Treatment Clinic of the University of Port Harcourt Teaching Hospital (UPTH), Nigeria. Eighty-one participants were enrolled: 63 were living with HIV (27 on short-term ART [less than six months], 36 on long-term ART [two years or more]), and 18 HIV-negative controls. Serum IL-6 and IL-10 were quantified by enzyme-linked immunosorbent assay (ELISA). Group differences were assessed using one-way analysis of variance (ANOVA), Tukey HSD post hoc tests, and independent samples t-tests. The influence of age and sex on cytokine levels was examined by analysis of covariance (ANCOVA). Results IL-6 was 7.35 ± 0.17 pg/ml in the short-term ART group, 6.38 ± 0.12 pg/ml in the long-term ART group, and 5.65 ± 0.15 pg/ml in controls. All three pairwise comparisons were statistically significant ( p < 0.05). IL-10 was 6.42 ± 0.15 pg/ml, 6.21 ± 0.11 pg/ml, and 5.81 ± 0.22 pg/ml across the same groups respectively. Only the comparison between the short-term ART group and controls was significant for IL-10. Age and sex had no statistically significant effect on either cytokine. Conclusion IL-6 declines with longer ART but remains elevated above control levels even after years of treatment, indicating persistent residual inflammation. Interleukin 10 is elevated in treated individuals compared with controls but does not track ART duration. These findings support the value of cytokine profiling as a supplementary tool for monitoring immune status in ART-treated PLHIV in a Nigerian clinical setting.