Differential expression of the calcium-binding proteins MRP8 and MRP14 in granulomatous conditions: an immunohistochemical study.

MRP14 and MRP8 are well-characterized calcium-binding proteins present in myeloid cells and mononuclear phagocytes. These antigens can easily be visualized in paraffin-embedded tissue, making use of monospecific polyclonal antibodies. This study evaluates MRP14 and MRP8 expression in mononuclear phagocytes in various granulomatous conditions. MRP14 is strongly expressed in all granulomatous conditions. MRP8 is variably expressed. Mononuclear phagocytes in granulomas of foreign body type, cat-scratch disease and erythema nodosum strongly express MRP8. In contrast, MRP8 expression is weak or absent in mononuclear phagocytes of sarcoidosis and tuberculosis. These results show differences in immunophenotype between non-phagocytic mononuclear phagocytes in delayed hypersensitivity type granulomas and phagocytic mononuclear phagocytes in non-hypersensitivity and non-immunological granulomas.