Antibody-dependent cell-mediated (K cell) cytotoxicity against isolated hepatocytes in chronic active hepatitis

Lymphocytes from 12 of 17 patients with chronic active hepatitis were cytotoxic towards isolated hepatocytes in a microcytotoxicity assay. Enriched fractions of B cells, prepared by removal of E-rosetted cells, were cytotoxic in all 12 cases, whereas T-cell fractions, prepared by removal of erythrocyte-antibody-complement-rosetted cells, were cytotoxic in only 1 case (P less than 0-0005). HBsAg positive and negative cases reacted similarly. In 6 patients the addition of 5 mug aggregated IgG significantly reduced cytotoxicity from 54% +/- 15 to 13% +/- 15 (mean +/- 1S.D.) suggesting that K cells may be the effector cell in an antibody-dependent, cell-mediated reaction directed against a liver-specific membrane lipoprotein.

Detection of HBSAG in fixed liver tissue - use of a modified immunofluorescent technique and comparison with histochemical methods

A modified immunofluorescent technique was used for the detection of HBSAg in formalin-fixed liver tissue, thereby allowing retrospective examination of paraffin sections and avoiding the need to split the sample at the time of biopsy. Comparison with two other methods, involving either orcein staining or standard haematoxylin and eosin (H and E) preparation for ground glass hepatocytes, showed slightly fewer positive hepatocytes in individual biopsies with the latter stain, but the specificity of both methods was high. In a series of 146 seropositive and 74 seronegative patients with a variety of liver disorders, hepatocytes positive for HBSAg were found in only one of 55 patients with acute hepatitis type B, whereas large numbers of positive cells were seen in all 22 healthy carriers of the surface antigen. In the 69 patients with chronic persistent or chronic aggressive hepatitis, the frequency of positive biopsies was 86% and 85% respectively. The positive cells in these cases were, in comparison with healthy carriers of HBSAg, much fewer in number and were scattered in random fashion throughout the lobule rather than occurring in discrete clumps or sheets. This variation in the intrahepatic expression of HBSAg may reflect differences in the immune response to hepatitis B viral antigens.

Chronic liver disease developing after outbreak of HBsAG-negative hepatitis in haemodialysis unit

Chronic liver disease developing after acute hepatitis type B is well documented, but is not thought to occur after acute hepatitis due to other viruses. However, follow-up of 29 patients in a haemodialysis unit who contracted HBsAg-negative acute hepatitis during 1968-70 revealed 8 cases with raised serum-aminotransferase levels dating from that time. Liver biopsy in 7 of these disclosed chronic aggressive hepatitis in 3, of whom 2 had already progressed to advanced cirrhosis. Chronic persistent hepatitis was present in 2 others, and the remaining 2 had non-specific hepatitis in association with massive iron overload. Immunological studies demonstrated a higher frequency of cellular immunity to HBsAg in those who had previously had acute hepatitis than in those who had not, although the prevalence of humoral antibody was similar in the two groups. One possible explanation for these findings is the presence of immunological cross-reaction at a cellular level between the hepatitis B virus and that responsible for the initial outbreak.

e Antigen-antibody system as indicator of liver damage in patients with hepatitis-B antigen

The clinical relevance of the e antigen-antibody system was investigated in 61 people persistently positive for hepatitis-B surface antigen, including 22 healthy carriers. The e antigen was not detectable in any of the healthy carriers, whereas it was found in 15 out of 28 patients with chronic aggressive hepatitis and two out of 11 with chronic persistent hepatitis. Its presence therefore indicates chronic liver disease but its absence does not exclude it. It may prove to be a particularly useful prognostic aid in chronic persistent hepatitis, since one of the two patients in whom it was found later developed aggressive hepatitis. In contrast, e antibody is of little diagnostic help, for, though it was found mostly in healthy carriers (18;82%), it was also detectable in 9 (23%) of the patients with chronic hepatitis. In 13 (76%) of the patients positive for e antigen Dane particles were seen on electron microscopy, but these were also present in 5 (19%) of the patients positive for e antibody. These findings are consistent with other evidence suggesting that e antigen is not a surface component of the Dane particle, but rather an independent soluble protein manufactured by the host in response to infection with the hepatitis-B virus.

Fulminant hepatic failure in leukaemia and choriocarcinoma related to withdrawal of cytotoxic drug therapy

In three patients with malignant disease HBsAg was detected in the serum at least 6 months before the development of acute hepatitis type B, which in each case followed a fulminant course to death. It is suggested that suppression of the normal immunological responses to hepatitis-B viral antigens by cytotoxic drug therapy permitted widespread infection of hepatocytes. Subsequently, upon withdrawal of these drugs, recovery of immunocompetence resulted in rapid destruction of all infected hepatocytes and massive liver damage. Screening for HBsAg before cytotoxic drug therapy, careful monitoring of liver function during its withdrawal, and prompt treatment with corticosteroids should abnormalities occur may prevent this unfortunate sequence of events.

Cell-mediated immunity to hepatitis B surface antigen in blood donors with persistent antigenaemia

Cellular immunity to the hepatitis B surface antigen (HBsAg) and a liver-specific lipoprotein was studied, using the leucocyte migration test, in 38 asymptomatic blood donors found to have HBsAg in the serum. Sensitization to HBsAg was found in 26% and was related to the presence of liver damage, being detected in 47% of those with elevated serum aspartate aminotransferase but in only 13% with normal enzyme levels. The frequency of sensitization to this antigen in those with chronic persistent or chronic aggressive hepatitis on biopsy was also higher than in those with unrelated or minimal changes. The findings using the liver-specific lipoprotein as antigen were similar and there was a correlation between the results obtained with this and the hapatitis B surface antigen. This study supports the hypothesis that a T-lymphocyte response to hepatitis B virus antigen can initiate an autoimmune reaction to antigens such as liver-specific lipoprotein on the hepatocyte surface, and that this reaction may be of importance in the production of chronic liver damage. In the absence of the T-cell response, the autoimmune reaction cannot occur and the virus is able to establish a harmless symbiotic union with the host.

Cellular and humoral immunity to hepatitis-B surface antigen in active chronic hepatitis

The hepatitis-B surface antigen (HBsAG) may be persistently present in the serum in a few cases of active chronic hepatitis but the cause of the disease in most patients is unknown. In a study of 39 HBsAg-negative cases cell-mediated immunity to HBsAg was observed in 24 (62%), suggesting a high frequency of previous infection with the hepatitis-B virus. Hepatitis-B surface antibody was detectable by radioimmunoassay in six patients, in all of whom complexes of HBsAg were present in the serum on electron microscopy. Out of 12 patients with HBsAg-positive active chronic hepatitis who were also studied eight, including all those untreated at the time, showed a cellular response to the antigen. Evidence of sensitization to a liver-specific cell surface lipoprotein was found with similar frequency in the two groups. These results are consistent with the hypothesis that hepatitis-B virus infection is important in initiating the disease in many cases of active chronic hepatitis and that sensitization to the liver cell membrane antigen is the autoimmune process responsible for the perpetuation of the liver injury.

Cell-mediated immunity to human Tamm-Horsfall glycoprotein in autoimmune liver disease with renal tubular acidosis

Cell-mediated immune responses to Tamm-Horsfall glycoprotein isolated from human urine were investigated using the leucocyte migration test. Abnormal responses were found in 91% of patients with active chronic hepatitis or primary biliary cirrhosis with an associated renal tubular acidosis (R.T.A.) but in only 19% of those without R.T.A. In nearly all of a group of patients without autoimmune liver disease and in a control group of normal subjects results were within normal limits. In addition, using an immunofluorescent technique with rabbit antibody to human Tamm-Horsfall glycoprotein, it was possible to show the presence in human liver cell membrane of material reacting immunologically as Tamm-Horsfall. These findings suggest that the development of an immune response to this glycoprotein, initiated by release of cross-reacting antigens from damaged hepatocytes, could be the mechanism underlying the occurrence of R.T.A. in some patients with autoimmune liver disease.

Histocompatibility antigens in active chronic hepatitis and primary biliary cirrhosis

The frequency of antigens HL-A 1 (48%) and HL-A 8 (52%) in 54 patients with active chronic hepatitis from south-east England was significantly higher than in 89 control subjects from the same region (22% and 17% respectively). No correlation could be detected with the age and sex of the patients or with the presence of a particular immunological abnormality but the frequency of HL-A 1 and HL-A 8 was much lower in the nine patients who were positive for HBAg than in the 45 HBAg-negative cases. These results provide further evidence of the importance of genetic factors in active chronic hepatitis. In contrast the frequency of HL-A 1 and HL-A 8 in primary biliary cirrhosis, both in 45 patients from south-east England and in 28 patients from western Scotland, was not significantly different from that found in control groups from the same regions.

The role of immunological mechanisms in acute and chronic hepatitis

Studies of asymptomatic carriers of hepatitis B antigen (HB Ag) have suggested that the hepatitis B virus may not be directly damaging to liver cells and it is possible that the hepatocellular necrosis which accompanies acute hepatitis may be induced by immunological reactions directed at viral antigenic determinants on the surface of infected cells.

Immunological reactions may also be implicated in the pathogenesis of active chronic hepatitis. Although antibodies which are commonly present in the serum are probably not of primary importance in the immunopathology, recent studies have demonstrated liver-specific immune responses, both humoral and cellular, which may be more directly related to the pathogenesis.

Cell-mediated immune response in primary biliary cirrhosis to a protein fraction from human bile

Cell-mediated immune responses to a protein fraction of human bile have been demonstrated, using the leucocyte migration test, in eight out of 10 patients with primary biliary cirrhosis but in only three out of nine with active chronic hepatitis. In the latter condition sensitization to a liver-specific hepatocellular antigen was found more frequently (five out of nine patients) than in primary biliary cirrhosis (two out of 10). These results, as well as the granuloma formation observed histologically, suggest that the initial bile duct lesion in primary biliary cirrhosis may be associated with a cell-mediated response to antigens-perhaps derived from bile duct epithelial cells-which may be normal constituents of hepatic bile.