Hepatitis B Virus DNA in Liver and White Blood Cells of Patients with Hepatoma

Abstract

Hepatitis B virus (HBV) DNA was studied in liver DNA of 23 patients with primary hepatocellular carcinoma and in white blood cell DNA of 11 of these patients by Southern blot hybridization analysis probed with 32P-labeled HBV DNA cloned in plasmid pBR325. Of the 23 hepatoma DNA samples, 16 were positive for HBV DNA, and 15 of these showed integration of HBV DNA into the host liver DNA. In 5 patients, free HBV DNA was found in addition to integrated HBV DNA and in only one was free HBV found alone. All patients serologically positive for HBV surface antigen (HBsAg) were positive for HBV DNA in tumor samples. The pattern and the degree of hybridization differed considerably among different cases. HBV DNA was found in tumor and in adjacent nontumor tissue in 2 patients. Of 11 white blood cell DNA samples, 2 were positive for HBV DNA. The HBV DNA in the white blood cells was not integrated into the host DNA. In the undigested white blood cell DNA, the free HBV DNA gave a positive signal at 5.5 kb [kilobase] and often also at 9.5 kb. After EcoRI digestion, these 5.5 kb and 9.5 kb positive fragments disappeared, while a strong positive band at 3.2 kb appeared. HindIII digestion produced the same positive fragments as in the undigested white blood cell DNA and failed to produce the 3.2 kb fragment. Sometimes, especially after HindIII digestion, a positive fragment at a position corresponding to .apprx. 16.2 kb was also demonstrable in addition to the 5.5 kb and 9.5 kb positive fragments. This is the 1st report of HBV DNA in leukocytes. HBV in leukocytes may represent a stage in the biology of HBV other than those in liver cells or serum. The finding of HBV in leukocytes of patients with hepatocellular carcinoma raises the possibility that leukocyte-borne HBV could mediate hepatocellular uptake of HBV. HBV in leukocytes may also possibly lead to leukocyte transformation and development of certain leukemias and lymphomas, supporting the hypothesis that HBV may be involved in the etiology of these diseases. HBV in leukocytes may play a role in the epidemiology of HBV and could impair leukocyte immunologic function.