Identification of factors influencing response rate to antiviral therapy of chronic hepatitis B virus infection. A review of the efficacy of adenine arabinoside and lymphoblastoid interferon in the Royal Free Hospital studies

We have reviewed the results of treating over 100 HBV carriers with adenine arabinoside, adenine atabinoside monophosphate and lymphoblastoid interferon. In the homosexual group of carriers, adenine arabinoside and its monophosphate have no value. However, in this group, lymphoblastoid interferon will produce a response in over 50% of cases. The lack of effectiveness of adenine arabinoside monophosphate in this group may stem from its immunosuppressant properties. In heterosexual carriers both adenine arabinoside monophosphate and lymphoblastoid interferon are effective in approximately 50-60% of cases. However, the response rate is different in the various racial groups. Northern European and Mediterranean people appear to respond whereas those from the Far East do not. This may reflect the fact that there are at least 2 mechanisms by which the chronic carrier state may arise. In 5-10% of adults, a relative deficiency of α-interferon production exists [37] and this defect is found in the majority of HBV carriers in Western Europe. In these, interferon acts as a replacement therapy and excellent results may be obtained if the patient is treated early in the course of the disease. It would appear that as the duration of the infection increases, the virus may integrate into interferon-reactive consensus sites and prevent the cell from responding to interferon. In patients infected at birth, transplacental anti-HBc appears to modulate the immune response and along with immaturity of the immune system at this age, results in failure to lyse infected cells. These patients do not benefit from interferon treatment: some form of immune manipulation is required. As in the infection acquired in adult life, the presence in the hepatitis B virus genome of an interferon-sensitive site, homologous to that found in the hepatocyte genome, will influence the biological response to interferon. It is now evident that there are several mechanisms underlying the chronic carrier state and that in different patients at varying stages of the infection, alternative approaches to therapy may be required.