Influence of Ethnicity in the Outcome of Hepatitis C Virus Infection and Cellular Immune Response

Abstract

This study was performed to examine the immunologic basis for the apparent ethnic difference in clinical outcome of hepatitis C virus (HCV) infection between African Americans (AA) and Caucasian Americans (CA). To this end, we recruited 99 chronically HCV-infected and 31 spontaneously HCV-cleared subjects for clinical, virologic, and immunologic analysis. In particular, CD4-proliferative T-cell response to genotype 1-derived HCV antigens (core, NS3-NS5) was examined in 82 patients chronically infected with genotype 1 (54 AA, 28 CA) and in all HCV-cleared subjects (14 AA, 17 CA). HCV-specific Th1 response also was examined in 52 chronic and 13 recovered subjects. Our results showed that HCV clearance was associated with a vigorous HCV-specific Th1 response irrespective of ethnic origin. Although the HCV-specific CD4 T-cell response clearly was weaker during chronic infection, AA ethnicity in this setting was associated with a significantly greater CD4-proliferative T-cell response to HCV, particularly to the nonstructural antigens (22% AA vs. 0% CA, P ‫؍‬ .007) as well as better clinical parameters of liver disease. Interestingly, most HCV-specific CD4 T-cell proliferative responses in AA patients were unaccompanied by concurrent interferon ␥ (IFN-␥) production, suggesting a dysregulated virus-specific, CD4 T-cell effector function during chronic HCV infection. In conclusion, our results suggest that host ethnicity does influence the clinical outcome and antiviral T-cell response during HCV infection. AA ethnicity is associated with a more robust antiviral CD4 T-cell response than CA ethnicity, although these T cells are limited in direct virus or disease control due to their dysfunctional nature. (HEPATOLOGY 2003;37:590-599.)

Peripheral virus-specific T-cell interleukin-10 responses develop early in acute hepatitis C infection and become dominant in chronic hepatitis

“…(3,(19)(20)(21) Overlapping HCV peptides 361 overlapping 15mer peptides (offset by 6 amino acid residues) spanning the entire HCV core and NS3-NS5 proteins based on HCV-H sequence (genotype 1a) were synthesized (Genemed, San Francisco, CA) and mixed into 12 separate pools containing 20-31 consecutive peptides/pool or 36 pools with 10-11 peptides/pool as previously described. (22,23) These peptides were immunogenic for CD4 + and CD8 + T-cells. (22,23) …”

“…(22,23) Cramp 2000 HCV-specific CD4 + proliferative T-cell response CD4 + proliferation assay was performed as previously described (3,22,23) with 2×10 5 cells/ well stimulated with recombinant HCV and control SOD proteins (10µg/mL) for 7 days, or phytohemagglutinin (PHA) at 2 µg/ml for day 4 days, with 16 hours of 3 H-thymidine uptake (1µCi/well) (Dupont NEN, Boston, MA). The results were expressed as a stimulation index (SI) with mean counts per minute (cpm) in stimulated wells divided by the mean cpm in control wells.…”

“…The results were expressed as a stimulation index (SI) with mean counts per minute (cpm) in stimulated wells divided by the mean cpm in control wells. (23) Cytokine Elispot Assay IL-10 and IFNγ Elispot assay was performed with 2×10 5 PBMC/well in triplicates as described previously. (23) HCV-specific CD4 + T-cell responses were examined using recombinant HCV and control proteins (10µg/ml).…”

“…HCV-specific total T-cell IL-10 and IFNγ responses were examined using overlapping HCV-derived 15mers (5µM/peptide) with positive controls including PHA (2µg/mL), tetanus toxoid (0.5µg/mL) and Candida albicans (20µg/mL). (22,23) IL-10 and IFNγ spot forming units (SFU) were counted using Elispot reader (Hitech Instruments, Media, PA). HCV-specific Tr1 or Th1 frequency was calculated by subtracting the mean SFU in negative control wells from mean SFU in antigen-stimulated wells and expressed as SFU/10 6 PBMC for each antigen or combined for total HCV-specific Tr1 or Th1 response (22,23).…”

“…(22,23) IL-10 and IFNγ spot forming units (SFU) were counted using Elispot reader (Hitech Instruments, Media, PA). HCV-specific Tr1 or Th1 frequency was calculated by subtracting the mean SFU in negative control wells from mean SFU in antigen-stimulated wells and expressed as SFU/10 6 PBMC for each antigen or combined for total HCV-specific Tr1 or Th1 response (22,23). The cut-off for a positive response for individual peptide pools was defined as >50 SFU/10 6 PBMC which was the 95% percentile for each peptide pool in 11 healthy controls.…”