Concentrations of soluble Fas and soluble Fas ligand as indicators of programmed cell death among patients coinfected with Human Immunodeficiency Virus and Hepatitis C Virus

Hepatitis C Virus (HCV) and Human Immunodeficiency Virus (HIV) coinfections can affect mechanisms of programmed cell death and therefore influence acquired immunodeficiency syndrome (AIDS) development as well as the course of chronic hepatitis C. The aim of the study was to assess soluble Fas (sFas) and soluble Fas ligand (sFasL) concentrations in HIV- and HCV-coinfected patients and, moreover, to establish their relationships with HIV viral load, CD4+ T lymphocyte count, as well as liver function tests. Seventy-eight patients were included in the study, among them 30 coinfected with HIV and HCV, 10 infected only with HIV, and 38 infected only with HCV. HIV infection was confirmed by means of Western blot analysis; HIV viral load was measured by RTPCR; and CD3+, CD4+, and CD8+ T lymphocyte counts were established by means of flow cytometry. HCV infection was confirmed through HCV RNA isolation, using RT-PCR. sFas and sFasL concentrations were measured in duplicate by ELISA. The mean CD4+ T lymphocyte count decreased in HIV- and HCV-coinfected patients versus HIV-infected individuals (429 versus 279/ml). sFasL protein was detectable principally in HIV-infected individuals without HCV infection (90%), whereas in those with HCV infection it occurred only in 11% of cases. The highest sFas concentration was observed in HCV-infected patients (25.9 ng/ml) as well as in HIV- and HCV-coinfected individuals (20.3 ng/ml). This concentration was negatively proportional to sFasL prevalence. The results of our study suggest that HCV infection in HIV-positive individuals may suppress processes of programmed cell death. There was no correlation between sFas, sFasL, and HIV-1 viral load. On the other hand, sFas concentration and the presence of sFasL were related to CD4+ T lymphocyte count.