Induction of latent membrane protein expression in in vitro Epstein-Barr virus-infected leukaemic B lymphocytes by interleukin 4 and antibodies to CD40.

Chronic lymphocytic leukaemia (CLL) B cells are clones representing the mature B cell phenotype. On infection with Epstein-Barr virus (EBV) CLL cells express the EB nuclear antigen (EBNA) complex but unlike EBV-infected normal B cells they do not express LMP nor do they proliferate or immortalize. Furthermore, EBV-CLL rapidly die by apoptosis in culture. In the present study we have used the B cell growth factors interleukin 4 and antibodies to CD40 to induce activation and proliferation of EBV-infected CLL cells. Although cell numbers did not significantly increase, apoptosis was partially inhibited in CLL cells which expressed increased levels of CD23 and were activated to immunoglobulin-secreting lymphoblasts. Expression of LMP was induced by interleukin (IL)-4 and anti-CD40 in all five EBV-infected CLL samples examined. However, this did not enhance cell proliferation or induce immortalization. Further analysis showed that LMP could be detected 4-5 days after EBV infection, and that both IL-4 and anti-CD40 could independently induce LMP but that their effect was additive. These results indicate that LMP expression is dependent on B cell activation processes and that in some circumstances full latent viral gene expression is not sufficient to cause B cell immortalization.

IgA class antibodies to hepatitis delta virus antigen in acute and chronic hepatitis delta virus infections.

Sera from 31 patients with chronic hepatitis delta virus infection and 18 patients with acute hepatitis delta virus infection were examined for IgA class antibodies to this virus using a newly developed enzyme immunoassay. IgA antibody to hepatitis D virus was detected in 21 (67.7%) of 31 patients with chronic delta viral hepatitis, but in only 1 (5.6%) of the 18 patients with acute infection (p less than 0.0005). Of the 21 patients with chronic delta hepatitis with IgA antibody to hepatitis D virus, 19 (90.5%) had moderate-to-severe activity on liver biopsy: 18 of the 21 had histological features of chronic active hepatitis and three had chronic lobular hepatitis. In all, 23 patients with chronic delta hepatitis had moderate-to-severe activity, and 19 (82.6%) had IgA antibody to hepatitis D virus. No statistically significant correlations were found between IgA antibody to hepatitis D virus and biochemical markers of liver injury (p greater than 0.4), or the presence of hepatitis delta virus antigen in liver biopsies (p greater than 0.2), in the patients with chronic delta hepatitis. The finding that IgA antibody to hepatitis D virus was almost exclusively associated with chronic hepatitis delta virus infection and correlated independently with moderate-to-severe histological activity (with a specificity of 90.5% and a sensitivity of 82.6%) suggests that this antibody might be a useful serological marker of underlying liver damage in chronic delta hepatitis.

Expression of intrahepatic hepatitis D viral antigen in chronic hepatitis D virus infection.

To elucidate the biological importance of intrahepatic hepatitis D virus antigen, its expression was correlated with biochemical and histological inflammatory activity in 98 biopsy specimens from 68 patients seropositive for total antibody to the virus. Seventy five specimens were positive for intrahepatic nuclear antigen for HDV antigen accompanied by cytoplasmic HDV antigen in only one biopsy specimen. This group had significantly higher serum transaminase activities and inflammatory activity than the remaining cases that were negative for HDV antigen. Among the group positive for HDV antigen, there was no correlation between the proportion of hepatocytes containing HDV antigen and either serum transaminase activity or histological inflammatory indices. In 22 HDV antigen positive patients who had follow up biopsy specimens taken at a median of two years, the proportion with cirrhosis increased from 36% to 73%. Serum transaminase activities remained the same during this period, but the proportion of HDV antigen positive cells dropped. Follow up of 51 patients showed that 21 died or underwent liver transplantation within three years. The absence of an association between intrahepatic HDV antigen expression and progression of histological liver damage does not support the view that HDV is directly cytopathic to hepatocytes. Immune mediated mechanisms may have a role in the pathogenesis of chronic liver disease related to HDV infection.

An enzyme immunoassay for detection of IgA class antibodies against hepatitis delta virus.

A sensitive and reproducible enzyme-linked immunoassay (ELISA) for IgA class antibodies against the Delta antigen (HDAg) is described. Specificity of the assay was demonstrated by the absence of binding to an unrelated antigen or to uncoated plates and the finding that binding to HDAg was independent of total IgA concentrations in sera. Positive results were obtained with sera from 11 of 14 patients with chronic Delta virus infection (seropositive for HBsAg and IgM anti-HDAg, negative for IgM anti-HBc) at serum dilutions of up to 1:10(6). Sera from four normal healthy individuals and from 25 patients with chronic hepatitis B or other liver disorders who had no evidence of exposure to HDV were all negative in the assay.

Significance of IgM anti-hepatitis D virus (HDV) in chronic HDV infection.

Intrahepatic hepatitis D virus (HDV) antigen (HDAg) and serum HDV RNA are excellent markers of active HDV replication but the relation of IgM anti-HDV to HDV replication and histological activity is less certain. To further elucidate the significance of serum IgM anti-HDV, 90 paired sera and liver biopsies from 64 patients seropositive for total antibody to HDV were analysed for IgM anti-HDV, intrahepatic HDAg expression, and histological inflammatory activity. IgM anti-HDV was strongly associated with intrahepatic HDAg expression with a sensitivity of 94.1% but the assay lacked specificity since 14 out of 22 cases negative for intrahepatic HDAg were also positive for IgM anti-HDV. In 20 patients in whom follow-up biopsies and paired sera were available, two patients lost intrahepatic HDAg but paired serum remained IgM anti-HDV positive. Although the presence of serum IgM anti-HDV correlated significantly with a higher histological inflammatory activity (P = 0.001), there was a considerable overlap with the group seronegative for IgM anti-HDV, again indicating a poor specificity. This lack of specificity of IgM anti-HDV for both HDV replication and histological activity indicates that this assay provides no additional information over and above assay for total antibody to HDV.

Hepatic histological findings after transplantation for chronic hepatitis B virus infection, including a unique pattern of fibrosing cholestatic hepatitis.

Long-term follow-up of 27 patients with hepatitis B virus-related chronic liver disease treated by transplantation showed that 23 had hepatitis B virus recurrence. In 13 patients late changes in the grafts were similar to those described in other series: minor abnormalities in five cases, chronic active hepatitis in five cases and non-hepatitis B virus-related graft dysfunction in three cases. Three patients had incomplete histological follow-up. Analysis of the histological changes and viral antigen expression in six cases revealed a distinct and novel pattern termed fibrosing cholestatic hepatitis. Development of fibrosing cholestatic hepatitis was associated with rapidly progressive graft dysfunction. It is postulated that this pattern of fibrosing cholestatic hepatitis develops because of a high cytoplasmic expression of viral antigens, including HBsAg. The remaining case had some features of fibrosing cholestatic hepatitis. The main histological features of this unique syndrome include thin, perisinusoidal bands of fibrosis extending from portal tracts to surround plates of ductular-type epithelium; prominent cholestasis; ground-glass transformation; and ballooning of hepatocytes with cell loss and mild mixed inflammatory reaction.