The density of tolerogenic immature CD1a+ dendritic cells (DC), and MARCO+, CD68+ and CD163+ tissue-associated macrophages (TAM) was analysed by immunohistochemistry in tissue micro arrays with tumours from 175 consecutive cases of periampullary adenocarcinoma who had undergone pancreaticoduodenectomy, 110 with pancreatobiliary type (PB-type) and 65 with intestinal type (I-type) morphology. The gene discussed is MARCO; the disease is periampullary adenocarcinoma.