306. CD8+ T-Cell Responses to Chronic Hepatitis C in Pregnancy

BACKGROUND: Chronic hepatitis C virus (HCV) infection is marked by stable, high -level viremia and a failed T-cell response. HCV-specific CD4+ helper T cells are rare, and CD8+ cytotoxic T cells are functionally exhausted or ineffective due to viral escape mutations. Postpartum, a subset of infected women experience a substantial drop in viremia. Preliminary data indicate that this unusual viral decline may be linked to a resurgence of HCV-specific CD4+ T cells producing Th1 cytokines. How improved CD4+ helper T-cell function might affect viral replication in this scenario is not established. Here we tested the hypothesis that improved CD4+ T cell help mediates control of chronic HCV replication through enhanced CD8+ T-cell function. METHODS: We examined plasma HCV RNA viral load (VL) and HCV-specific T-cell responses in 33 women with chronic HCV during the third trimester (T3) and at 3 months postpartum (3P). HCV-specific CD4+ and CD8+ T-cell IL2 and IFNγ responses were measured by intracellular cytokine staining following stimulation of peripheral blood mononuclear cells with peptide pools corresponding to the HCV proteins NS3, NS4a, and NS4B. RESULTS: Median VL dropped from 5.87 log(10) at T3 to 5.25 log(10) at 3P (P < 0.0001, Wilcoxson signed rank), with a wide range from +0.4 log(10) to -4.2 log(10). The degree of decline correlated significantly with improved frequencies of HCV-specific CD4+ T cells producing IFNγ (P = 0.015 Spearman) but did not correlate with CD8+ T-cell changes. Nevertheless, improved T helper function correlated with increased HCV-specific CD8+ T-cell function (ΔCD4+IL2+ vs. ΔCD8+IFNγ+, P = 0.015 Spearman, graph 1; ΔCD4+IFNγ+ vs. CD8+IFNγ+ at 3P, P = 0.004 Spearman, graph 2). CONCLUSION: Despite no significant association between virus-specific CD8+ T-cell Tc1 cytokine production and postpartum viral control, our data suggest that recovery of CD4+ T-cell help may augment CD8+ T-cell function. Further study incorporating viral genomic sequences to focus on intact class I epitopes is needed to clarify the relationship of improved CD8+ function and viral control in this unique model of immune restoration. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.