The foam cells of monocyte/macrophage origin are positive for KP1, HAM56, CD11b and CD68 as pointed out by Nakashiro et al. in xanthogranulomatous cholecystitis).[20] Many T lymphocytes were identified by these authors positive to CD4 and CD8. Macrophages and T lymphocytes demonstrated a marked expression of HLA-DR antigen. A delayed type hypersensitivity reaction of cell mediated immunity has been suggested in the pathogenesis of xanthogranulomatous cholecystitis.[20]