Controlling mature CD4+ T cell responses

T cell receptor excision circles (TRECs), CD4+, CD8+, and their CD45RO+, and CD45RA+, subpopulations in hepatitis C virus (HCV)-HIV-co-infected patients during treatment with interferon alpha plus ribavirin: analysis in a population on effective antiretroviral therapy

Interferon (IFN)-alpha induced CD4(+) T lymphopenia is a toxic effect of the treatment of chronic hepatitis C virus (HCV) in human immunodeficiency virus (HIV)-co-infected patients. To increase the knowledge about this secondary effect, we performed an analysis of the evolution of the T cell receptor excision circles (TRECs), CD4(+) and CD8(+) T cells and of their CD45RO(+) and CD45RA(+) subpopulations during the treatment of chronic hepatitis HCV with peginterferon alpha (pegIFN-alpha) + ribavirin. Twenty HCV/HIV-co-infected patients, with undetectable HIV load after highly active antiretroviral therapy (HAART), were treated with pegIFN-alpha + ribavirin. TRECs were determined using real-time polymerase chain reaction. CD4(+) and CD8(+) T cells and their CD45RO(+) and CD45RA(+) subpopulations were analysed by two-colour flow cytometry. Median baseline CD4(+) and CD8(+) T cells were 592 mm(3) and 874 mm(3), respectively. Median baseline CD45RO(+) subpopulation was 48% for CD4(+) T and 57% for CD8(+) T lymphocytes. A progressive decrease in both T cell populations, as well as of their CD45RO(+) and CD45RA(+) subpopulations, was detected, with a difference between the baseline and nadir levels approaching 50%. The evolution of T cell populations and TRECs was independent of the response to the treatment. T lymphocytes and their subpopulations returned to baseline levels at 24 weeks after the end of treatment, with the exception of the T CD4(+) CD45RA(+) subpopulation. The ratio of CD4(+) CD45RO(+)/CD4(+) CD45RA(+) increased from 0.89 (baseline) to 1.44 (24 weeks after the end of the therapy). TRECs/ml did not return to the basal values. In conclusion, a significant reduction of CD4(+) and CD8(+) T cells, and of their CD45RA(+) and CD45RO(+) subpopulations, in HIV/HCV co-infected patients treated with pegIFN-alpha was observed. Both subpopulations increased after the suppression of treatment, but the CD4(+) CD45RA subpopulation did not reach the basal levels as a consequence, at least in part, of a decrease in thymic production.