CD4+ and CD8+ T Cell Activation in Children with Hepatitis C

Area of Science:

• Immunology
• Virology
• Pediatrics

Background:

• Chronic hepatitis C virus (HCV) infection in adults is associated with T cell exhaustion.
• The immune status of children with HCV infection, particularly their T cell populations, is not well understood.
• Children with HCV infection exhibit a higher rate of spontaneous viral clearance compared to adults.

Purpose of the Study:

• To investigate T cell activation and exhaustion in children with chronic HCV infection.
• To evaluate the functional response of peripheral T cell populations in pediatric HCV.
• To compare T cell phenotypes between children with and without HCV, and with adults with chronic HCV.

Main Methods:

• Peripheral blood mononuclear cells were isolated from 16 children with HCV, 16 age- and sex-matched controls, and 20 adults with chronic HCV.
• Multiparameter flow cytometry was employed to analyze T cell populations.
• Characterization included assessment of naive T cells, activation/exhaustion markers (e.g., programmed cell death-1), and cytokine production (interferon gamma, interleukin-2).

Main Results:

• Children with HCV had reduced naive T cells and increased activation/exhaustion markers on CD4(+) and CD8(+) T cells compared to controls.
• Functional T cell activation was suggested by transcription factor analysis in children with HCV.
• Enhanced production of interferon gamma and interleukin-2 was observed specifically in the CD4(+) T cell subset of children with HCV.

Conclusions:

• Pediatric HCV infection is characterized by distinct T cell phenotypic changes, including increased programmed cell death-1 expression, similar to adult responses.
• Increased cytokine production by CD4(+) helper T cells in children with HCV may impact long-term prognosis.
• These findings highlight a unique immune profile in children with chronic HCV, distinct from both healthy children and adults with chronic infection.