Background: In our previous histological analyses, RCAS1-positive macrophages were not detected on biopsy samples from patients with inflammatory liver diseases, if their inflammation was not severe; that is, serum alanine aminotransferase (ALT) levels of less than 200 IU/L. In contrast, Fas ligand (FasL)-positive mononuclear cells including macrophages were detected
in most of the samples regardless of serum ALT levels.
Case Report: We immunohistochemically assessed the expression of RCAS1, FasL, and a specific marker for macrophages (LN-5) in liver biopsy samples from 2 patients, a 51-year-old woman with acute on chronic hepatitis B and a 52-year-old man with autoimmune hepatitis, in whom severe inflammation was present before starting medical treatment. FasL- and/or RCAS1-positive macrophages were infiltrated mainly at the areas of hepatocytic damage.
FasL-positive macrophages increased in proportion to serum transaminase levels. In contrast, few RCAS1-positive macrophages were detected near the peak of inflammation but their numbers increased during the recovery phase.
Conclusions: The number of FasL- and RCAS1-positive macrophages showed positive and negative correlation with the degree of inflammation, respectively. Both FasL and RCAS1 are apoptosis-inducing molecules, however, target cells of each may be different in hepatitis.

Keywords: Hepatitis B