Evaluation of langerhans cell infiltrate by CD1a immunostain in liver biopsy for the diagnosis of primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is characterized by chronic nonsuppurative destructive cholangitis, which is considered to be a cell-mediated immune reaction. Antigen-presenting cells, including Langerhans cells and dendritic cells, have been found in portal tracts and in bile duct epithelium and may play a role in the pathogenesis of PBC, but the importance of identifying these cells for diagnosing PBC has not been studied yet. In this study, we sought to evaluate the importance of identifying Langerhans cells using a CD1a immunostain in the diagnosis of PBC. Liver biopsies from adult patients diagnosed with PBC (n=60), primary sclerosing cholangitis (n=29), obstructive cholangitis (n=13), chronic viral hepatitis B or C (n=19), autoimmune hepatitis (AIH, n=15), acute cellular rejection (n=11), and chronic rejection (n=10) at our institution were retrospectively reviewed. An immunohistochemical stain for CD1a was used to detect Langerhans cells, and the distribution of CD1a-positive Langerhans cell infiltrate was recorded as lobular, portal with bile duct sparing, and intraepithelial. Intraepithelial Langerhans cells were identified in 58% of PBC including antimitochondrial antibody-negative PBC and PBC-AIH overlap cases, 14% of primary sclerosing cholangitis, 15% of obstructive cholangitis, 9% of acute cellular rejection, 6% of AIH, and no cases of chronic viral hepatitis or chronic rejection. The number of intraepithelial Langerhans cells was significantly higher in PBC than in other conditions, with the mean number of CD1a-positive intraepithelial Langerhans cells per bile duct in PBC calculated as 2.2 compared with <1 per duct for the other control cases. Thirty-three of 60 (55%) PBC cases showed at least one bile duct containing ≥2 CD1a-positive Langerhans cells. This was statistically significant (P<0.01) when compared with control groups. The overall sensitivity and specificity of using ≥2 CD1a-positive Langerhans cells per bile duct as the diagnostic criteria for PBC were 55% and 96%. Given the heterogenous nature of liver involvement by PBC, a review of cases with morphologic features of duct damage yielded an increased sensitivity (79%) with no reduction in specificity. In conclusion, the detection of a Langerhans cell infiltrate of ≥2 cells by CD1a in a given bile duct on needle biopsy may be a valuable tool in the diagnosis of PBC.