XANTHOGRANULOMATOUS CHOLECYSTITIS - CELL COMPOSITION AND A POSSIBLE PATHOGENETIC ROLE OF CELL-MEDIATED-IMMUNITY

Thirty-three cases of xanthogranulomatous cholecystitis (XGC) exhibiti ng the typical morphologic features were studied by tight and electron microscopy and immunohistochemical techniques. Incidence of XGC was 4 .2% of the surgically resected gallbladder diseases. Histologically, t he granulomatous lesion of XGC principally consisted of accumulations of foam cells and lymphocytes. Variable numbers of multinucleated gian t cells, granulocytes and fibroblastic cells were also noted. With res pect to the origin of foam cells, it was considered that the vast majo rity of foam cells were derived from monocytes/macrophages because the y were invariably positive for KP1, HAM56, CD11b and CD68. Intersperse d among macrophage foam cells, many T lymphocytes were identified. The subtyping of T cells indicated a heterogenous population composed of both CD4+ and CD8+ lymphocytes typically in a ratio of 1:2. Macrophage s and T lymphocytes demonstrated a marked expression of HLA-DR antigen . Electron microscopic and immunohistochemical double-staining observa tion demonstrated intimate apposition of T lymphocytes to macrophages or macrophage foam cells, The results indicate that XGC is a granuloma tous disorder characterized by accumulations of macrophage foam cells and T cells. Delayed type hypersensitivity reaction of cell-mediated i mmunity may be implicated in the pathogenesis of XGC.