Increased S-100 protein-immunoreactivity of Kupffer cells is associated with lymphohematological malignancy

The distribution of S-100 protein in normal tissue has been studied extensively. However, little is known about its expression in pathologic states. The aim of the present study was to investigate the expression of S-100 protein in diseased human liver, especially in Kupffer cells. One hundred cases of autopsy livers originating from patients with various diseases were examined. Increased S-100-immunoreactivity of Kupffer cells was observed in six cases. Of the six cases, four were derived from a lymphohematologic malignancy, such as B cell lymphoma, B cell lymphoblastic leukemia, multiple myeloma and chronic myelogenous leukemia with lymphoblastic crisis. Lymphohematologic malignancy accounted for 16 out of the 100 cases examined. Thus, increased S-100-positive Kupffer cells was significantly associated with lymphohematologic malignancy (P < 0.01); 25% (4/16) in cases with lymphohematologic malignancy versus 2.4% (2/84) in the remaining cases. Moreover, some of these S-100-positive Kupffer cells were positive for S-100 beta-subunit, which is not normally expressed by Kupffer cells. Although the reason for this increased S-100-immunoreactivity is speculative, the authors' hypothesis is that tumor cells may produce some factor(s) that induce the expression of S-100 protein in Kupffer cells.