Important note: Information in this article was accurate in December 2000. The state of the art may have changed since the publication date.
Encouraged by the relative success of interferon and ribavirin for hepatitis C virus infection, doctors in Spain have also tested this combination against hepatitis B virus (HBV) infection. The doctors reported detailed results on 18 male subjects with chronic HBV infection. Although no subject was co-infected with HIV, the results from this study may be of interest to co-infected PHAs. All subjects received 5 million units of interferon-alpha three times weekly along with 1 to 1.2 grams/day of ribavirin, for 12 months. Doctors then monitored subjects for a further 12 months.
A year after subjects stopped taking combination therapy, technicians could not detect HBV in blood samples from 12 of the 18 subjects. In seven of the 12, liver enzyme levels were still higher than normal. These elevated liver enzymes suggest that HBV infection continued despite treatment. In the remaining five subjects liver enzyme levels were normal. Thus, only five of 18 (28%) subjects for whom data were available developed a sustained response and were considered cured.
Interferon and ribavirin are usually considered antiviral agents, but readers should be aware that these drugs can have a complex effect on the immune system. In fact, by interfering with the immune system, interferon activates the body's antiviral defenses. The results from this study are encouraging and could be tested in people co-infected with HIV and HBV.
The Spanish team suspects that combination therapy helped the immune system suppress production of a chemical called IL-10 (interleukin-10). All the people who recovered from HBV infection produced low levels of IL-10 while those who did not recover produced increased amounts of this chemical signal. As well, T-cells in those who recovered were better able to recognize and fight HBV than in those who did not recover. Again, this probably had something to do with IL-10 levels. The improved response by T-cells likely played an important role in helping to suppress HBV. The role played by IL-10 in the immune system is increasingly being recognized by researchers. This chemical signal, or cytokine, likely also plays a key role in the fight between HIV and the immune system.
1. Rico MA, Quiroga JA, Subirá D, et al. Hepatitis B virus-specific T-cell proliferation and cytokine secretion in chronic hepatitis B e-antibody-positive patients treated with ribavirin and interferon alfa. Hepatology 2001;33:295-300
2. Pawlotsky J-M. Hepatitis C virus resistance to antiviral therapies. Hepatology 2000;32(5):889-896.
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