Autoimmune Hepatitis

Autoimmune Hepatitis results from breach of immune tolerance to hepatocyte-specific antigens, leading to autoreactive CD8+ T cells attacking liver cells and autoantibodies against liver cell components. Two main types are recognized: Type 1 AIH (anti-smooth muscle antibodies and/or anti-nuclear antibodies) and Type 2 AIH (anti-liver-kidney-microsomal antibodies). The pathophysiology involves failure of regulatory T cell function, overactivation of effector T cells, and breakdown of immune tolerance. Genetic predisposition (HLA alleles) and environmental triggers (infections, medication) likely play roles in disease initiation. AIH presents with variable severity from mild chronic hepatitis to fulminant liver failure. Many patients are asymptomatic until advanced disease, discovered through abnormal liver enzymes on routine screening. Symptomatic presentations include fatigue, jaundice, right upper quadrant pain, and arthralgias. Histologically, the liver shows interface hepatitis with portal inflammation. Without treatment, progressive fibrosis leads to cirrhosis and portal hypertension with ascites, hepatic encephalopathy, and liver failure. Immunosuppressive therapy with corticosteroids and azathioprine is effective, inducing remission in 60-80% of patients. However, relapse is common upon therapy withdrawal. Disease activity fluctuates, requiring monitoring of transaminases and immunoglobulin levels.