Effects of the CCR5-Δ32 mutation on hepatitis C virus-specific immune responses in patients with haemophilia

In hepatitis C virus (HCV) infection antiviral T cells express the CC chemokine receptor 5 (CCR5). Their recruitment to the liver is an important step in the immune response. A 32 base pair deletion in the CCR5 gene leads to reduced expression and total loss of CCR5 in CCR5-Δ32 heterozygous and homozygous subjects, respectively. However, the role of this mutation for antiviral immunity remains unclear. Here, we analysed proliferation, IFN-γ and IL-4 secretion (ELISpot) induced by the HCV antigens core, NS3, NS4, and NS5a in 21 anti-HCV-positive haemophiliac patients in relationship to their CCR5 genotypes (CCR5 wildtype n = 10, CCR5-Δ32 heterozygous n = 5 and CCR5-Δ32 homozygous n = 6). Furthermore, T cell migration in response to the CCR5 ligands CCL3, -4 and -5 was studied. Overall IFN-γ responses to HCV proteins were only slightly greater in CCR5 wild-type patients than in CCR5-Δ32 carriers (0.6 versus 0.24 SFC/104 PBMC; p = 0.043). This difference was consistently seen with all tested HCV antigens. In contrast, neither T cell migration, nor PBMC proliferation, nor IL-4 production differed between CCR5 genotypes. Interruption of the CCR5 signalling pathway due to CCR5-Δ32 may potentially result in subtle reduction of HCV specific IFN-γ responses in anti-HCV-positive haemophiliac patients.