Influence of GB virus C on IFN-γ and IL-2 production and CD38 expression in T lymphocytes from chronically HIV-infected and HIV-HCV-co-infected patients

Study design may explain discrepancies in GB virus C effects on interferon-γ and interleukin-2 production and CD38 expression in T lymphocytes

“…GBV-C coinfection was not associated with lower immune activation in human immunodeficiency virus (HIV)-positive individuals as measured by CD38 expression per cell and IL-2 and IFN-γ expressing cells in their study. We agree with Baggio-Zappia et al (2011) that “several factors, such as differences in the study populations, the stage of HIV infection and the time of GBV-C acquisition, may account for the discrepant results reported by different research groups”. However, two major factors may confound interpretation of the results reported by Baggio-Zappia et al and provide the most likely explanation for the discrepant results observed between this study and previous reports (Maidana-Giret et al 2009, Baggio-Zappia et al 2011).…”

“…cART lowers T cell activation, raises CD4 counts, decreases HIV VL and thus interferes significantly with other factors associated with HIV disease progression (Autran et al 1997, Carcelain et al 2001, Lederman 2001). Since the vast majority of subjects in the study of Baggio-Zappia et al (2011) were effectively treated by cART, it is not surprising that GBV-C did not have an observed effect on the clinical variables studied (CD4, HIV VL etc. ).…”

“…Since cART will lower detection of cell surface markers of T cell activation, making detection of a diminution by GBV-C more difficult to detect, and since frozen PBMCs can alter levels of T cell activation markers, we believe that the study of Baggio-Zappia et al (2011) does not negate the prior studies that used fresh PBMCs to evaluate T cell activation. However, the results illustrate the need for more direct and thorough studies of GBV-C on T cell function in individuals with HIV-infection.…”

“…Recently, Baggio-Zappia et al (2011) reported the effects of GB virus C (GBV-C) on interleukin (IL)-2 and interferon (IFN)-γ in CD4 and CD8 T cells. GBV-C coinfection was not associated with lower immune activation in human immunodeficiency virus (HIV)-positive individuals as measured by CD38 expression per cell and IL-2 and IFN-γ expressing cells in their study.…”

“…Secondly, Baggio-Zappia et al (2011) froze the peripheral blood mononuclear cells (PBMCs) prior to conducting in vitro studies of activation, IL-2 and IFN-γ cytokine production. Freeze-thawing PBMCs can alter detection of both surface marker expression and T cell function (Kvarnstrom et al 2004, Mallone et al 2011).…”