The isolation of a marker antigen from rat liver and pancreas tissue, which reacts with antibodies in a subtype of autoimmune hepatitis by complement fixation test, enzyme-linked immunosorbent assay and Western blot, is described. The liver-pancreas antigen could be detected in tissue from different human or animal organs, but liver and pancreas yielded the highest activity. A highly specific antigen fraction was obtained by gel filtration and ion exchange chromatography with a 100,000 g supernatant from rat liver tissue, and this preparation was shown to be devoid of nuclear, mitochondrial and microsomal antigens and cytokeratin 8 and 18, as demonstrated by appropriate marker antibodies. These data and absorption studies with cell organelles indicate that liver-pancreas antigen is a cytosolic protein. By Western blotting, two major epitopes at molecular weights 52 kD and 48 kD could be visualized. Sera from 175 patients previously shown to have high complement-fixing activity to a nonpurified liver-pancreas antigen fraction were further analyzed. All were positive by enzyme-linked immunosorbent assay with the purified liver-pancreas antigen fractions, and 111 were also positive by Western blot. Eighty-six sera reacted with the 52-kD determinant, 33 with the 48-kD determinant and 2 with both determinants. In 117 of the 175 patients, antibody to liver-pancreas antigen was associated with other autoantibodies known to characterize subgroups of autoimmune hepatitis. Thus 19 patients had antibodies to nuclei and 96 to actin but none to liver-kidney microsomes, hereby suggesting that antibody to liver-pancreas antigen may define another subgroup of autoimmune hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS)

The humoral response components of an aqueous mistletoe extract (HM) was evaluated in 23 tumor patients who had been treated from 2 months up to 6 years with increasing dosages of HM. IgG antibodies against mistletoe lectin and other components of this extract were detected by ELISA, immunodiffusion, and blotting technique, using either the aqueous extract (HM) or a purified lectin preparation (ML). Their activity depended upon dosage of HM and length of therapy. No anti-HM/ML antibodies of the IgM type could be detected. Immunoblotting revealed lectin-specific antigens at 62 kD, 33k D, and 29 kD. In the presence of ML or HM, PHA-induced proliferation of normal lymphocytes was decreased in a dose-dependent manner; this effect was neutralized by adding the IgG fraction from pooled anti-HM-antibody-positive sera, indicating that the cytotoxic effect of lectins was eliminated by these specific antibodies. In view of these findings, it is questionable whether exposing tumor cells to mistletoe extracts in vivo exerts the same direct effect on tumor cells that is observed in vitro.

A new complement-fixing antimitochondrial antibody--anti-M8--was detected in patients with primary biliary cirrhosis. Anti-M8 was only found in association with anti-M2, however, not all anti-M2 positive patients had anti-M8. Thus, among 66 anti-M2 positive patients, 29 were also positive for anti-M8, whereas sera from patients who had the complement-fixing anti-M2 and anti-M4 antibodies in parallel always strongly reacted with the M8 antigen. This group was previously described as mixed form. The M8 antigen was isolated either from human liver mitochondria or pig kidney microsomes and could be clearly distinguished from the M4 antigen. In contrast to M4, M8 was trypsin sensitive and banded at sucrose densities from 1.16 to 1.24, while M4 was found at densities from 1.08 to 1.14. Like M4, the M8 antigen also co-purified with outer mitochondrial membranes. Fifty-three patients with primary biliary cirrhosis have been followed over a period of up to 16 years and were classified according to their complement-fixing antimitochondrial antibody profile. At the time of the first diagnosis, 95% of 31 patients being anti-M2 positive, but anti-M8 negative (antimitochondrial antibody Profile I) were in Stage I or II. In contrast, only 61% of 13 patients being anti-M2 and anti-M8 positive (antimitochondrial antibody Profile II) and 44% of 9 patients with anti-M2, anti-M8 and anti-M4 in parallel (antimitochondrial antibody Profile III) belonged to Stage I or II.(ABSTRACT TRUNCATED AT 250 WORDS)

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