Metastasis to the liver often occurs in patients during the natural course of pancreatic cancer. Using carcinoma cell lines established from 9 such patients, we examined phenotypes of cell lines to search for correlations with their potential to metastasize to the liver. Anti-asialo GMI-treated nude mice were used. PCI-43, -55, -24 and -6, in this order, had frequent metastases, while PCI-10, -19, -35, -64, and -66 did not. In vitro doubling time, surface expression of sialyl Lewis(a) (SLe(a)), VLA-4/6, LFA-I/3, CEA, E-selectin, VCAM-I, NCAM, Mac-I, HLA-ABC/ DR/DQ, ICAM-I/2, production of interleukin-I alpha, tumor necrosis factor-alpha, and matrix metalloproteinase, as well as susceptibility to cytotoxicity by natural killer cells, were all examined. Expression of surface SLea was significantly associated with metastasis; numbers of metastatic colonies of SLe(a)-positive and -negative cell lines were 21.6 +/- 33.9 and 6.5 +/- 14.3 (p < 0.01), respectively. Moreover, the intensity of surface SLe(a) expression of each PCI line correlated with the number of metastatic colonies in the liver. When anti-SLe(a) monoclonal antibody (MAb) was administered, the development of liver metastasis by PCI-43 cells was significantly repressed, as compared with a control MAb. Although a reverse correlation between surface ICAM-I expression and liver metastasis was noted, the species-restricted function of ICAM-I makes interpretation difficult. Collective evidence indicates that expression of SLe(a) is an important positive mediator in the hematogenous metastasis of pancreas carcinoma.