Giorgina Mieli-Vergani*, Diego Vergani **
Institute of Liver Studies,
King's College Hospital, London. *, Institute of Liver Studies,
King's College Hospital, London. **
Autoimmune liver disorders are inflammatory liver diseases characterized histologically by a dense mononuclear cell infiltrate in the portal tract and serologically by the presence of non-organ and liver specific autoantibodies and increased levels of immunoglobulin G (IgG), in the absence of a known etiology. They usually respond to
immunosuppressive treatment, which should be instituted as soon as diagnosis is made. The onset of these conditions is often ill-defined, frequently mimicking acute hepatitis and the previously accepted requirement of six month duration of symptoms before a diagnosis of autoimmune disease could be made has been abandoned. Liver disorders in which the liver damage is likely to arise from an autoimmune attack include autoimmune hepatitis (AIH) and autoimmune sclerosing cholangitis (ASC).
Autoimmune hepatitis: Two types of AIH are recognized according to seropositivity for smooth muscle and/or antinuclear antibody (SMA/ANA, type 1 AIH) or liver kidney microsomal type 1 antibody (LKM1, type 2 AIH). There is a female predominance in both. LKM1 positive patients tend to present more acutely, at a younger age and commonly have IgA deficiency, while duration of symptoms before diagnosis, clinical signs, family history of autoimmunity, presence of associated autoimmune disorders, response to treatment and long-term prognosis are similar in the two groups.
Autoimmune Sclerosing cholangitis: The most common type of sclerosing cholangitis in childhood is autoimmune sclerosing cholangitis (ASC), an overlap syndrome between autoimmune hepatitis and sclerosing cholangitis. The clinical, biochemical, immunological and histological presentation of ASC is often indistinguishable from that of AIH. In both conditions, there is an increase in IgG, presence of circulating non-organ specific autoantibodies, and inflammatory histological features, including interface hepatitis. A prospective study over a period of 16 years in our unit has shown that children with ASC respond to immunosuppressive treatment with prednisolone and azathioprine satisfactorily and similarly to AIH in respect to remission and relapse rates, times to normalization of biochemical parameters, and decreased inflammatory activity on follow up liver biopsies. However, the cholangiopathy can progress on treatment, suggesting that prednisolone and azathioprine are effective in abating the parenchymal inflammatory damage, but may not be as effective in controlling the bile duct disease. Moreover, there may be evolution from AIH to ASC over the years, despite treatment.
Whether the juvenile autoimmune form of sclerosing cholangitis and AIH are two distinct entities or different aspects of the same condition, remains to be elucidated.
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