Whipple's disease: morphologic and immunofluorescence characterization of bacterial antigens.

The bacterial etiology of Whipple's disease is generally accepted. However, the exact identity of the "Whipple bug" has remained elusive. Indeed, the isolation of several types of bacteria from different patients with Whipple's disease has caused some to speculate that Whipple's disease may have polymicrobial etiology. Our light and electron microscopic studies document the presence of bacilliform organisms lying free in the lamina propria of the duodenal mucosa. Intact and partially degraded bacterial organisms were seen in the phagosomes of macrophages. Indirect immunofluorescence studies demonstrated the presence of multiple bacterial antigens in the lamina propria as well as the macrophage granules. This profile of antigens is similar to the profile demonstrated in four other patients in two previous studies. The occurrence of similar profiles of bacterial antigens in the tissues of different patients with Whipple's disease suggests a single microorganism in the etiology of Whipple's disease. Because of the overlapping features of muciphages and Whipple's cells in the rectal biopsy material, the superiority and reliability of proximal small intestinal biopsy in preference to rectal biopsy are re-emphasized.