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home - Liver - Autoimmune Conditions - Autoimmune Hepatitis Written by Dr Sebastian Zeki
Knowledge


Recognises and appropriately investigates patients with auto-immune
liver diseases

Aware of management and complications of autoimmune liver
disease including extra-hepatic manifestations and associations
including malignant complications in PSC

Skills
Appreciates and understands that this range of liver disease is
frequently under-diagnosed and may have been inappropriately
managed

Selects appropriate immunomodulatory therapy has awareness of
side effects and may well require specialist care

Behaviours
Responds urgently to the management challenge of these severe and
often acute diseases and involves more specialist services where
required

Autoimmune Hepatitis

The damage caused by drug-induced AIH stops after drug cessation. Anti-CYP2D6 In type 2 AIH, anti-LKM-1 directed vs epitope of CYP2D6 (cytochrome P450IID6) Written by Dr Sebastian Zeki There are weaker associations with HLA-class I MICA genes, the promoter region of tumor necrosis factor alpha and complement genes (class III).Non-HLA loci.IgG and TCR loci also relevant for genetic predisposition. MHC Class 2 Histological features:Portal mononuclear lymphoplasmacytic cell infiltrate.Occasional eosinophils invade the sharply demarcated hepatocyte boundary (limiting plate) surrounding the portal triad and into the surrounding lobule (periportal infiltrate) and beyond.Periportal lesion (=piecemeal necrosis/interface hepatitis), spares biliary tree but may involve more of the lobule.There may also be centrizonal necrosis.Bile duct changes (destructive and nondestructive cholangitis and ductopenia)in 25%.Plasma cell infiltrate, rosettes of hepat-cytes, and multinucleated giant cells, may be seen. Bridging fibrosis occurs leading to cirrh-sis. Soluble liver antigen and liver-pancreas antigen (IgG1)Specific for AIH- in both type 1 +2 AIH.Possibly viral origin Asialoglycoprotein receptor= liver-specific membrane protein expressed in high density in the periportal hepato-cytes. Pathogenesis Immune regulatory mecha-nismsCD8 Suppression of CD4 response may be defectiveThere may also be a sponta-neous immunosuppression that occurs when the condition is in remission CD8-Regulate CD4 response CD4= Effector Cells responsible for ongoing necro-inflammatory response(oligoclonality for CDR region 3 (V3).) Hepatocyte RELEVANT AUTOANTIGENS Triggering factors:Measles, Hepatitis, HSV, EBV, CMV- probably by molecular mimicry.Oxyphenisatin, methyldopa, nitrofurantoin, diclofenac, minocycline, and possibly statins- can also cause AIH type damage.Interferon- can unmask or induce autoimmunity eg tx of viral hep may unmask AIH. Genetic PredispositionHLA determinantsType 1 AIH is associated with HLA-DR3 more common in early onset severe form and HLA-DR4 (more late-onset and higher extrahepatic manifestations) and better steroid response).Type 2 AIH is associated with HLA-DRB1*07, HLA-DRB1*03 and DQB1*0201 alleles.In Japan, Tyoe 2 AIH is associated with HLA-DR4. Autoimmune Hepatitis = Chronic active hepatitis/ =Lupoid hepatitis

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