Detection and characterization of liver membrane autoantibodies in chronic active hepatitis by a solid-phase radioimmunoassay

A solid-phase radioimmunoassay was developed to detect antibodies to liver membrane antigens in sera of patients with HBsAg-negative and -positive liver diseases and primary non-hepatic autoimmune diseases. Ten of fourteen patients with HBsAg-negative CAH had autoantibodies detected by RIA; negative results were obtained with sera of seven patients with HBsAg-positive acute and chronic liver diseases, six patients with miscellaneous liver diseases, including two patients with PBC, two healthy blood donors and seven patients with primary non-hepatic autoimmune diseases. Antibodies detected by RIA correlated with liver membrane autoantibodies (LMA) found by indirect immunofluorescence; no correlation was observed with AMA, ANA and SMA. Species-cross-reacting antibodies could be absorbed by preincubation with isolated plasma cell membranes prepared from rabbit livers. Liver membrane autoantibodies detected by RIA were directed against three different antigen fractions obtained from Sepharose 6B chromatography including LSP and LM-Ag. Only three of ten antibodies were directed against species-specific determinants; others cross-reacted with rabbit antigens. Only the antibody to LSP was organ-specific, all others cross-reacted with kidney proteins. Ferritin, human serum albumin and human plasma lipoprotein were excluded as target antigens. Although several sera reacted with identical molecules a remarkable heterogeneity of liver membrane autoantibodies was observed.

Autoantibodies against liver-specific membrane lipoprotein in acute and chronic liver diseases: studies on organ-, species-, and disease-specificity

A double antibody radioimmunoprecipitation test was used to detect anti-human LSP, anti-rabbit LSP, and autoantibodies against the human kidney equivalent of LSP (anti-HKP) in patients' serum. Anti-human LSP was found in 27/62 cases with chronic active liver disease (CALD), 9/16 cases with chronic persistent hepatitis (CPH), and 14/33 patients with acute viral hepatitis (AVH), 2/10 patients with ;inactive' cirrhosis of the liver (Ci), 4/14 patients with alcohol induced liver disease (ALD), 1/7 patients with miscellaneous liver diseases (MLD), and in 6/58 patients with primary non-hepatic autoimmune disease (PNHA). Frequencies of anti-LSP did not depend on HBsAg status. Anti-rabbit LSP was detected in only 9% of patients with AVH as compared with 42% for anti-human LSP. No such difference was observed in the other groups of patients. Anti-HKP was found in 6/62 patients with CALD, 1/7 patients with MLD, and 2/58 patients with PNHA; no anti-HKP occurred in patients with CPH, AVH, ALD, and Ci. The frequency of anti-LSP was not correlated with the presence of non-organ-specific autoantibodies in patients with CALD; furthermore, no correlation with sex-distribution, age, gammaglobulin levels, and SGOT occurred in this group of patients. No correlation existed between anti-LSP and liver membrane autoantibodies detected by indirect immunofluorescence on isolated rabbit hepatocytes (LMA). The reported data show that naturally occurring anti-LSP, characteristic for acute and chronic inflammatory liver diseases, are mostly directed against organ-specific determinants of the LSP complex. It is suggested that the occurrence of antibodies to species-specific determinants of LSP reflects a transient state of autoimmunity. The LMA immunofluorescence test seems to detect antibodies against other liver membrane antigens as well as LSP.

Treatment of diabetes insipidus complicated by diabetes mellitus with chlorpropamide and clofibrate

A patient with severe idiopathic diabetes insipidus, complicated by diabetes mellitus, was first treated with a combination o clofibrate and chlorpropamide. Urine volume dropped from 18 litres/day (CH2O = 10.5 ml/min) to 3.1-5.1 litres/day (CH2O = -0.1 -+1.1 ml/min) under treatment. Ten months after the beginning of therapy treatment was maintained with chlorpropamide alone; no significant rise in urine volume was observed. After 18 months when therapy was stopped for 5 days urine volume rose to 11.7 litres/day maximum (CH2O = 6.6 ml/min). No obvious side effects occurred under treatment during a follow up for over 18 months. Serum levels for arginine vasopressin before and under treatment were below 1.0 pg/ml. Determination of free water clearance (CH2O) proved to be a highly sensitive and simple method for follow up controls. It is discussed whether the coincidental manifestation of diabetes insipidus and diabetes mellitus may be caused by a single molecular lesion. This hypothesis is supported by data which imply that in both disease chlorpropamide acts via a common molecular mechanism, the blocking of endogenous prostaglandin E2 biosynthesis. Finally a treatment with oral "non-hormonal" drugs like clofibrate and chlorpropamide should be taken into consideration in some cases of diabetes insipidus as is demonstrated by this case report.

The liver specific protein: evidence for species-specific and non-species-specific determinants

Liver specific protein (LSP) is known to be a macrolipoprotein of complete organ-specificity but without complete species-specificity. This membrane antigen is believed to play an important role in the pathogenesis of human and experimental chronic active hepatitis (CAH). In the present study, we investigated the species-crossreactivity of LSP by crossed immunoelectrophoresis, tandem crossed immunoelectrophoresis and fused rocket immunoelectrophoresis. With a sheep anti human LSP serum, two determinants of human LSP could be detected--one was found to be species-specific, the other crossreacted with rabbit, rat, swine and mouse LSP; no reaction was found with bovine and sheep LSP. A rabbit anti human LSP serum, after short term immunization, reacted only with a species-specific determinant of human LSP, no species-crossreactivity was observed. In contrast, rabbits with experimentally induced CAH, after longterm immunization with human LSP, had developed an autoantibody to rabbit LSP in addition to antibodies to the species-specific determinant of human LSP. Antibodies to the liver membrane antigen (LM-Ag) could not be detected. In conclusion human LSP contains a species-specific and a non-species-specific determinant. CAH in rabbits is induced by the loss of tolerance to the non-species-specific determinant.

LM-Ag and LSP--two different target antigens involved in the immunopathogenesis of chronic active hepatitis?

Two different types of immune reactions against liver membrane antigens have been described: firstly, cell-mediated immunity and autoantibodies against the liver-specific protein (LSP) in HBsAg-negative and HBsAg-positive chronic active hepatitis (CAH), and secondly, a liver membrane autoantibody (LMA) in HBsAg-negative CAH. Using 100,000 g supernatants of human and rabbit liver homogenates, the corresponding antigen of LMA could be separated by affinity chromatography on insolubilized LMA-positive sera from patients with HBsAg-negative CAH. A further characterization by crossed immunoelectrophoresis showed that LMA is directed against a soluble liver membrane antigen (LM-Ag) that is not a constituent of the purified LSP. LM-Ag seems to be species-unspecific and moves faster than LSP and serum albumin in crossed immunoelectrophoresis. While LSP is believed to be involved in the pathogenesis of HBsAg-negative and HBsAg-positive chronic active hepatitis, LM-Ag may be a target antigen only in cases of HBsAg-negative autoimmune CAH.

Digoxin and digitoxin elimination in man by charcoal hemoperfusion

Since there is no widely used causal means of reducing the severity of massive digitalis intoxication the capability of hemoperfusion with coated activated charcoal to remove toxicologically relevant amounts of digoxin and digitoxin was evaluated in vitro and in man. At a blood flow rate of 100 ml/min the digoxin clearance by hemoperfusion in vitro was 51 +/- 8 ml/min in comparison to 24.3 +/- 11.3 ml/min by hemodialysis. The average hemoperfusion clearance of digitoxin was 31.7 +/- 13.4 ml/min, whereas almost no digitoxin was removed by hemodialysis. These clearance values point to the ability of hemoperfusion of eliminating digitalis glycosides from the blood. They do not clarify the essential question whether it is possible to lower the toxic concentrations in the tissues.

Arrhythmias and inhibition of noradrenaline uptake caused by tricyclic antidepressants and chlorpromazine on the isolated perfused rabbit heart

1. Isolated rabbit hearts were perfused with a modified Tyrode solution containing noradrenaline in concentrations increasing stepwise from 5.9 nM to 5.9 muM at 5 min intervals. This dose regime was applied twice before and once 20 min after starting perfusion with one of 9 tricyclic drugs. Ventricular rate and right atrial and ventricular tensions were recorded using the transverse method. 2. Infusions of noradrenaline evoked ventricular arrhythmias in hearts perfused with amitriptyline 4.8 muM, chlorpromazine 5.0 muM, desipramine 5.0 muM, dibenzepine 34.7 muM, doxepin 4.7 muM, imipramine 4.7 muM, noxiptiline 9.1 muM and opipramole 9.2 muM. The incidence of arrhythmias increased with the concentration of noradrenaline applied and the dose of tricyclic drug administered. Whenever arrhythmias had started they continued as long as noradrenaline was infused. Noradrenaline failed to produce arrhythmias in hearts not exposed to drugs and after iprindole 4.7 muM or cocaine 2.9-18 muM. 3. Propranolol 0.1 muM inhibited the incidence of arrhythmias after doxepin 4.7 muM plus noradrenaline 5.9-190 nM. 4. Neuronal uptake of exogenous noradrenaline in the rabbit heart was inhibited by the tricyclic drugs in the following order of declining p potency: doxepin, noxiptiline, amitriptyline, desipramine, chlorpromazine, imipramine, dibenzepine, opipramole and iprindole. 5. Among tricyclic drugs the potency to inhibit amine uptake is related to the incidence of arrhythmias evoked by a submaximal concentration of noradrenaline. It appears, however, that these two parameters are not causally linked. 6. The isolated rabbit heart perfused with noradrenaline might be used as a model for testing the arrhythmogenic actions of tricyclic drugs and the treatment of such arrhythmias.