The pathological appearance of hyaline droplets in Kupffer cells is not specific to patients with autoimmune hepatitis.

The roles of Kupffer cells in the pathogenesis of autoimmune hepatitis (AIH) remain uncertain. In this study, pathological significance of hyaline droplets in Kupffer cells was investigated in patients with AIH, primary biliary cholangitis (PBC), AIH/PBC overlap syndrome, chronic hepatitis C (CH-C) and nonalcoholic steatohepatitis (NASH). Hyaline droplets in Kupffer cells were commonly observed in 14 of 22 (64%) patients with AIH and 4 of 4 (100%) patients with AIH/PBC overlap syndrome. However, the emergence of hyaline droplets in Kupffer cells was not associated with the severity of histological fibrosis or activity in patients with AIH. Serum immunoglobulin G (IgG) levels and titers of antinuclear antibodies (ANAs) did not affect the presence of hyaline droplets in Kupffer cells among AIH patients. Moreover, hyaline droplets in Kupffer cells were also present in eleven of 20 (55%) patients with PBC, four of 24 (17%) patients with CH-C and six of 15 (40%) patients with NASH. The existence of hyaline droplets in Kupffer cells was independent of serum IgG levels and seropositivity for ANAs in those subjects. These results suggest that the pathological appearance of hyaline droplets in Kupffer cells may not be specific to AIH, and that the emergence of hyaline droplets in Kupffer cells may be independent of autoimmune responses, including serum IgG levels and titers of ANAs, and hepatic fibrosis and activity in AIH patients. Further studies will be required to clarify the pathological relevance of hyaline droplets in Kupffer cells.