Antigenicities of enteropathogenic Escherichia coli, lysozyme, and alpha-1-antichymotrypsin on macrophages of genitourinary malacoplakia.

Seven cases of genito-urinary malacoplakia were analyzed histologically, ultrastructurally and immunohistochemically in a comparison with two cases of xanthogranulomatous pyelonephritis. Immunohistochemically, von Hansemann cells and Michaelis-Guttmann bodies, both hallmarks for the diagnosis of malacoplakia, showed a common antigenicity for enteropathogenic Escherichia coli as cytoplasmic granules of varying sizes. These microscopic manifestations corresponded ultrastructurally to a series of phagolysosomal degradations of coliform bacilli. Serogroups against E. coli OK antigens, which were positive for malacoplakic cells, were not confined to a particular group. Macrophages of xanthogranulomatous pyelonephritis did not show the E. coli antigenicity. Antigenicity of lysozyme and alpha-1-antichymotrypsin on the von Hansemann cells was equivocal, but these enzymes were strongly positive on macrophages of xanthogranulomatous pyelonephritis. The macrophages of both malacoplakia and xanthogranulomatous pyelonephritis were positive for antihuman macrophage antibody. These results indicate that malacoplakia depends mainly on infection by a non-specific strain of enteropathogenic E. coli and may arise from defective digestive enzyme activity of infiltrating macrophages. Immunohistochemical analysis using antisera against E. coli OK antigens, lysozyme and alpha-1-antichymotrypsin was useful in identifying the prediagnostic stage of malacoplakia and in differentiating the lesion from xanthogranulomatous pyelonephritis.