Diagnostic utility of IgG and IgM immunohistochemistry in autoimmune liver disease

Figure 1 Immunoglobulin expression in autoimmune hepatitis and primary biliary cirrhosis. IgG-positive plasma cells (A) outnumber IgM-positive plasma cells (B) in most cases of autoimmune hepatitis (AIH); In contrast, IgM-positive plasma (C) cells predominate over IgG-positive cells (D) in the majority of cases of primary biliary cirrhosis (PBC). IgG background staining within sinusoids and blood vessels is common due to the presence of serum IgG. (Immunohistochemistry, 400 × magnification).

Figure 2 IgM/IgG ratio distinguishes the majority of cases of primary biliary cirrhosis (IgM/IgG ratio ≥ 1) from all other groups (IgM/IgG ratio < 1). Single outlier in the AIH group was diagnosed with AIH-PBC sequential syndrome based on subsequent serology and pathological data (see discussion). Abbreviations: PBC: Primary biliary cirrhosis; AIH: Autoimmune hepatitis; PSC: Primary sclerosing cholangitis; CHC: Chronic hepatitis C.