Adefovir dipivoxil (bis-POM PMEA) is an adenine nucleotide analogue with activity against retroviruses and herpesviruses, and in vitro activity against hepatitis B virus (HBV). This study was conducted to evaluate its safety and antiviral activity in patients with chronic HBV infection. Twenty patients (13 co-infected with human immunodeficiency virus, HIV) were randomized in a phase I/II, double-blind, placebo-controlled study. Patients who had been hepatitis B surface antigen (HBsAg)/hepatitis B e antigen (HBeAg) positive for > or = 6 months, with elevated hepatic transaminases and serum HBV DNA > or = 50 pg ml-1, were randomized to adefovir dipivoxil 125 mg (n = 15) or placebo (n = 5) as a single, daily, oral dose for 28 days. Antiviral activity was assessed by changes in serum HBV DNA (using the Digene Hybrid Capture assay) and HBeAg/hepatitis B e antibody (HBeAb) status. HBV DNA levels fell rapidly by > 1 log10 in all active drug recipients (median fall 1.8 log10 pg ml-1) but increased by 0.01 log10 pg ml-1 in controls (P = 0.002). Reductions were sustained during treatment. HBV DNA returned to baseline over 1-6 weeks following discontinuation of active drug. HBeAg became transiently undetectable in one patient on treatment and, in another, sustained seroconversion to HBeAb occurred 12 weeks after treatment ended. Liver transaminase elevations > 300 U l-1 were observed in three patients during therapy (leading to protocol-specified treatment discontinuation or dose reduction) and in four patients during follow-up. On-treatment transaminase elevations were associated with HIV status, occurring in three of six HIV-uninfected patients compared with none of nine who were HIV infected. In addition, a slower return to baseline of serum HBV DNA levels was observed in the non-HIV-infected patients. Treatment for chronic hepatitis B as a once-daily oral dose was well tolerated and associated with significant and sustained reductions in serum HBV DNA levels during treatment. Transaminase elevations, which may be related to the therapeutic effect, were observed during and after treatment. Further studies are warranted to investigate the safety, and optimum dose and duration, of adefovir dipivoxil treatment for chronic hepatitis B.

H epatitis B virus (HBV) is a noncytopathic DNAvirus, which can cause acute, self-limited hepatitis or chronic hepatitis, cirrhosis, and/or hepatocellular carcinoma. 1 The diversity of clinical outcomes after exposure to HBV is determined primarily by the host immune response. 2,3 The resolution of HBV infection after acute self-limited hepatitis is associated with strong CD4ϩ and CD8ϩ T-cell responses, with a type 1 cytokine profile. [4][5][6][7] In contrast to this strong antiviral T-cell reactivity, which persists in the convalescent phase after hepatitis B surface antigen (HBsAg) clearance, patients with chronic HBV infection have weak or undetectable T-cell reactivity to HBV, which is the dominant factor that permits an ongoing, high level of viral replication. A series of investigations of the mechanisms by which Tcells control HBV replication showed the major role of cytokine-mediated, intracellular inactivation of HBV that does not require cell death. 8 This noncytolytic antiviral effect, first demonstrated in an HBV transgenic mouse model and subsequently in other animals, is primarily mediated by interferon-gamma (IFN-␥). 9-11 A detailed analysis of HBV clearance during acute infection in chimpanzees showed that the disappearance of viral DNA from the liver coincides with IFN-␥ induction before the increase of serum alanine aminotransferase (ALT), in other words, without destruction of hepatocytes. 11

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SUMMARY The mean small intestinal intraepithelial lymphocyte count in seven children with untreated cow's milk protein intolerance (CMPI) on a milk-containing diet was significantly higher than 22 control children also having a milk-containing diet. Ten milk-intolerant children on a milkfree diet had a mean intraepithelial lymphocyte count which was significantly lower than the level in the 22 control children on a milk-containing diet. When these 10 children were challenged with cow's milk they relapsed clinically, and in every case the intraepithelial lymphocyte count rose, although it remained within normal limits. Nineteen children on milk-free diets who had recovered from CMPI had a mean lymphocyte count which was also significantly lower than controls on normal diets, suggesting that when milk is removed from the diet the lymphocyte count is low regardless of whether the child is milk sensitive or not. The reaction of intraepithelial lymphocytes to milk in CMPI is markedly different from their response to gluten in coeliac disease.