K.T. Nouri-Aria

ENHANCED TUMOUR NECROSIS FACTOR AND INTERLEUKIN-1 IN FULMINANT HEPATIC FAILURE

Sepsis and endotoxaemia are common in fulminant hepatic failure (FHF) and may contribute to multisystem disease in such patients. Tumour necrosis factor (TNF) is a probable mediator of endotoxic shock and infusion of this monokine into animals causes multi-organ failure that shares features with FHF. In patients with FHF, TNF production was increased and correlated closely with activity of interleukin-1, another cytokine that is released by monocytes/macrophages in response to infection and endotoxin and is produced in increased quantities in FHF. Interleukin-2 activity was impaired in FHF and correlated negatively with TNF production.

CONTRASTING RELATIONS BETWEEN SUPPRESSOR-CELL FUNCTION AND SUPPRESSOR-CELL NUMBER IN CHRONIC LIVER DISEASE

75 patients with various chronic liver diseases were investigated by simultaneous assay of suppressor-cell function and enumeration of suppressor T cells by monoclonal antibody. In chronic active hepatitis and primary biliary cirrhosis, substantial defects in suppressor-cell function were associated with negligible alterations in the proportions of suppressor cells. Defective suppressor-cell function was also evident in most patients with HBsAg-positive liver disease and in some with alcoholic liver disease. While the expected relations between suppressor-cell function and the proportions of helper or suppressor cells and the helper/suppressor ratio were apparent in alcoholic liver disease, the results in the HBsAg-positive, HBeAg-positive patients were in direct contrast. This apparent anomaly may reflect functional heterogeneity of the lymphocyte population detected by the monoclonal antibody OKT8, which identifies suppressor and cytotoxic cells. This study demonstrates that in the absence of simultaneous measurement of function, enumeration of T-cell subsets with monoclonal antibodies is an inadequate assessment of immunoregulatory balance.

T and B cell function in alcoholic liver disease

Increased in vivo synthesis of immunoglobulin in patients with alcoholic liver damage has been attributed to direct activation of B cells, although other defects of lymphocyte function have been identified suggesting a more generalised defect. In the present study we have investigated the role of T cell regulation of immunoglobulin production in alcoholic liver disease analysed according to the presence or absence of alcoholic hepatitis. Spontaneous production of IgG and IgA was elevated and co-culture experiments confirmed hyper-reactivity of B cells, but also suggested impaired T cell function. Suppressor cell activity for IgG and IgA was impaired. Similarly, the response to pokeweed mitogen for IgG and IgA was defective, although this was more marked for secretion than for proliferation suggesting an associated T helper defect. No differences in the immunological abnormalities were identified between those with alcoholic hepatitis and those with other alcoholic liver diseases. This study demonstrates a broad defect of T cells and a hyper-reactivity of B cells in patients with alcoholic liver disease, irrespective of the severity of hepatic inflammation.

HLA A1-B8-DR3 and Suppressor Cell Function in First-Degree Relatives of Patients with Autoimmune Chronic Active Hepatitis

The relationship between suppressor T cell function and the inheritance of the A1, B8, DR3 haplotype was studied in 17 healthy, first-degree relatives of patients with autoimmune chronic active hepatitis. A marked defect in suppressor cell function was found significantly more often in A1, B8, DR3-positive relatives (5 of 7) compared with those who were A1, B8, DR3-negative (1 of 10; P = 0.017). Less marked abnormalities were also found in the A1, B8, DR3-negative relatives compared with A1, B8, DR3-negative control subjects. The results indicate that the defects in suppressor cell function in patients with untreated chronic active hepatitis result from the inheritance of genetic factors linked to the major histocompatibility complex and other gene loci and are not secondary to hepatic inflammation.

In vitro α-interferon treatment of peripheral blood mononuclear cells improves interleukin-2 activity in HBV-related chronic liver disease

Summary To investigate mitogen-induced helper T cell activity in patients with HBV-related chronic liver disease (CLD), Interleukin-2 (IL-2) activity was assessed by an IL-2 bioassay using phytohaemagglutinin (PHA)-stimulated mononuclear cells (MNC). IL-2 activity was significantly reduced in patients with CLD ( P α -interferon ( α -IFN) showed the highest IL-2 activity. In vitro preincubation of MNC with α -IFN before stimulation with PHA, led to a significant increase in IL-2 activity in all subjects ( P α -IFN may be, in part, responsible for the therapeutic effect of this agent in HBV-related CLD.

In vitro effects of lymphoblastoid interferon on lymphocyte activation and cell-mediated cytolysis in patients with chronic hepatitis B virus infection

In addition to a direct anti-viral effect, interferons have important immunological properties including effects on cell-mediated immunity and antibody production as well as cell-mediated cytolysis. In chronic hepatitis B virus infection the host immune system is important for the elimination of replicating virus and in addition to directly inhibiting hepatitis B virus replication, interferons may affect host immune responses. We investigated the effect of lymphoblastoid interferon in vitro on lymphocyte activation and cell-mediated cytolysis in patients with chronic hepatitis B virus infection. The proliferative response to the mitogen PHA was significantly impaired in patients compared to controls. In addition supernatants of cultured mononuclear cells from patients stimulated with PHA contained less interleukin-2 activity than controls while the proportion of stimulated mononuclear cells expressing the interleukin-2 receptor was also reduced in patients. Prior incubation with 10(3) U ml-1 lymphoblastoid interferon increased both interleukin-2 activity and interleukin-2 receptor expression in patients and controls, although in patients the response was less marked. In contrast the proliferative response was unaffected. Natural killer cell activity against K562 cells was similar in patients and controls which in both groups was significantly augmented by prior incubation with 10(3) U ml-1 lymphoblastoid interferon; the increase was inversely proportional to baseline activity. In contrast incubation of target or effector cells with interferon did not augment T-cell cytotoxicity against autologous hepatocytes. The effects of lymphoblastoid interferon in vitro, were modest, but subtle changes in immunological status in addition to a direct effect on viral replication may be relevant to eventual clearance of the hepatitis B virus.

The relationship between HLA-DR3 and T-cell regulation of immunoglobulin production in primary sclerosing cholangitis

Immunoglobulin production in vitro, its control by concanavalin A-activated suppressor T-cells, and the relationship between abnormalities in nonantigen-specific suppression and histocompatibility antigens have been studied in 20 patients with primary sclerosing cholangitis (PSC). Suppression of IgG, IgM, and IgA synthesis was impaired in 12 patients with PSC alone, but was normal in 8 with PSC and associated ulcerative colitis (UC). The HLA antigens B8 and DR3 were increased in frequency in both groups of patients, but an association between DR3, and to a lesser extent B8, and defective suppressor T-cell function was only observed in the patients with PSC alone. These results not only provide further evidence of an association between HLA DR3 and impaired nonantigen-specific suppression but also indicate the genetic complexity of this association and its specificity, being found in this study in only one subgroup of patients with PSC.

Differential effect of α-interferons on CD4- and CD8-positive lymphocytes in chronic hepatitis B virus carriers

Summary α -Interferons are an effective therapy in a proportion of chronic hepatitis B virus (HBV) carriers. The mode of action is almost certainly dependent upon immune modulation in addition to direct antiviral effects but the precise mechanism is unknown. To investigate whether the aberrant T-cell activation present in HBV carriers was responsive to interferons, we have studied the in vitro effect of α -interferons on Tac antigen expression and DNA synthesis as early and late markers of T-cell activation, respectively. At a concentration of 1000 U/ml the effect of α -interferons on Tac expression was contrasting in the two major T-cell subsets; there was enhancement of Tac expression on CD4-positive T-cells but inhibition of the CD8-positive subset. However, there was no overall effect on lymphocyte proliferation, perhaps as a consequence of the differential effect of α -interferons on the early T-cell activation marker. At higher concentration, however, the enhancement of T-cell activation was less clear, indicating that the concentration range that supports T-cell activation is narrow. Such subtle differential effects on T-cell activation may be accompanied by more profound effects on immune function and this may be one way in which α -interferons are of value in chronic HBV infection.

Hepatic alpha-interferon expression in cytomegalovirus-infected liver allograft recipients with and without vanishing bile duct syndrome.

SummaryIn previous studies cytomegalovirus (CMV) infection was identified as one risk factor in the development of vanishing bile duct syndrome (VBDS) after orthotopic liver transplantation (OLT), but its precise role in relation to the pathogenesis of tissue damage is uncertain. In the present study a-interferon (α-IFN) expression in the liver was studied as an indirect marker of viral infection in serial liver biopsies from 42 patients following OLT. α-IFN was identified more frequently in the bile duct cytoplasm of patients developing VBDS, with or without evidence of preceding CMV infection (7/8 and 4/5 cases, respectively), when compared with patients with acute CMV but without evidence of VBDS (6/19 cases; P<0.05) or those with neither complication (2/10 cases; P<0.01). α-IFN was detectable in bile duct cytoplasm for a longer period in patients developing VBDS than in those with acute CMV infection alone (median 14 weeks and range 9–19, median 6 weeks and range 1–11 weeks, respectively; P< 0.025). These data indicate that persistent CMV infection of bile duct cells is a likely co-factor linked to progression to VBDS, but the processes that allow persistent viral infection and bile duct destruction remain to be determined.