Immune Factors Linked to Long-Term HCV Humoral Memory Five Years After Cure in People with HIV: A Cross-Sectional Study.

Background: The immunological factors associated with long-term hepatitis C virus (HCV)-specific humoral immunity after cure remain uncharacterized, particularly in people with HIV (PWH). This study investigated T-cell immunophenotypes and plasma biomarkers associated with anti-E2 binding (HCV-E2Abs) and neutralizing antibody (HCV-nAbs) titers 5 years after achieving sustained virologic response (SVR). Methods: This cross-sectional study analyzed 64 PWH with cured HCV and prior advanced fibrosis. We quantified plasma antibody titers against 5 HCV genotypes, T-cell phenotypes (n = 58), and plasma biomarkers (n = 50). Associations were assessed using Generalized Linear Models (gamma distribution, log-link function) adjusted for clinical confounders, reporting adjusted Arithmetic Mean Ratios (aAMRs) and false discovery rate (FDR)-corrected q-values. Results: Higher frequencies of CD4+ T-cell activation (CD38+; aAMR = 1.58; q = 0.028) and soluble CD27 levels (aAMR = 1.46; q = 0.038) were associated with higher HCV-E2Abs titers. In contrast, memory T-cell activation across CD4+ and CD8+ compartments (HLA-DR+ and CD38+; all q < 0.10) and elevated soluble immune checkpoints (sCD28, sPD-L2, sLAG-3, sCTLA-4; all q < 0.10) were associated with preserved HCV-nAbs titers. Conversely, a higher frequency of naïve CD8+ T-cells was associated with lower neutralization capacity (aAMR = 0.41; q = 0.042). Regarding inflammatory markers, soluble TNF-RI was positively associated with neutralizing titers (aAMR = 1.44; q = 0.019), whereas IL-18 was inversely associated (aAMR = 0.53; q = 0.019). Conclusions: Specific activated T-cell subsets, checkpoint shedding, and selective inflammatory signals were associated with higher long-term HCV-nAbs titers in PWH. In contrast, higher frequencies of naïve CD8+ T-cells and elevated IL-18 levels were associated with reduced neutralizing capacity.