Premalignant lesions and hepatocellular carcinoma in a non-cirrhotic alcoholic patient with iron overload and normal transferrin saturation

A 66-year-old white man had a hepatic resection for a 6-cm well-differentiated hepatocellular carcinoma which had developed in a non-cirrhotic liver. The only risk factors found were heavy drinking, smoking and heterozygosity for the C282Y mutation of the HFE gene. The liver was mildly fibrotic and overloaded with iron. It also contained numerous iron-free hepatocellular lesions from <1 to 10 mm, suggesting a premalignant change. These lesions were of three types: (i) iron-free foci, (ii) hyperplastic nodules and (iii) dysplastic nodules with severe dysplasia or even foci of well-differentiated grade I hepatocellular carcinoma. This observation suggests the possibility of malignant transformation of the liver in the newly-described syndrome of iron overload and normal transferrin saturation. It also illustrates the multistep process of carcinogenesis in the non-cirrhotic liver.

Aspirin and heparin prevent hepatic blood stasis and thrombosis induced by the toxic glycoprotein Bolesatine in mice

Bolesatine is a toxic glycoprotein isolated from Boletus satanas Lenz, which inhibits protein synthesis in vivo and in vitro. The LD50 (24 h) is 1 mg /kg bw (i.p.), in mice and rats. When given i.p. to mice (0.1 - 1.0 mg/kg bw) bolesatine induced thrombi and blood stasis in the liver, 5 - 21 h after injection, and modifications of the number of blood corpuscles in peripheral blood. These effects were efficiently reversed by aspirin, ticlopidin and heparin (as attested by histology and electron microscopy) which however failed to prevent death in animals given lethal doses. Together, these results showed that the death of bolesatine poisoned animals given high doses, was rather due to a combination of thrombosis and other toxic effects. In addition, they suggest that these antithrombotic drugs may overcome cases of human poisoning, with low exposures of this boletus, showing a hypertension probably due to mechanical obstruction which resists normal therapy.

Case report: secondary biliary cirrhosis possibly related to congenital hepatic fibrosis. Evidence for decreased number of portal branch veins and hypertrophic peribiliary vascular plexus

A 30-year-old man with presinusoidal portal hypertension was transplanted for cryptogenic cirrhosis. On the explanted liver, few intrahepatic stones, biliary cirrhosis, chronic cholangitis of the large bile ducts and a peculiar proliferation of small dilated bile ducts at the periphery of the portal tracts led to the diagnosis of secondary biliary cirrhosis and cholangitis, possibly linked to ductal plate malformation, including congenital hepatic fibrosis associated with a minor form of Caroli's disease. Ex vivo portogram and histology showed the paucity of portal vein branches and the hypertrophy of the peribiliary vascular plexus. This hypertrophy, which has been reported in livers with presinusoidal hypertension, is another indirect argument to suggest the diagnosis of congenital hepatic fibrosis.

Localized fibrous tumor of the liver: imaging findings

We report the imaging of a localized fibrous tumor of the liver, focusing on color Doppler US, CT, MR imaging, and angiographic findings. We discuss the differential diagnosis of such a rare, benign lesion of the liver. Detailed imaging of this tumor has not been reported in the literature previously.

Human hepatic myofibroblasts increase invasiveness of hepatocellular carcinoma cells: evidence for a role of hepatocyte growth factor

The stroma of hepatocellular carcinomas (HCC) is infiltrated with myofibroblasts (MFs). Preliminary in vivo data have suggested that liver MF express hepatocyte growth factor (HGF), a cytokine that has been implicated in several tumor models. Our aim was to investigate the role of MF and HGF in HCC. Cultured liver MF expressed HGF messenger RNA (mRNA) and secreted HGF in their medium, as shown by Western blot, immunoprecipitation, and enzyme-linked immunosorbent assay (ELISA). Addition of MF-conditioned medium to the HepG2 HCC cell line induced cell scattering. This was associated with a decrease in cell proliferation. MF also increased about 100-fold the ability of HepG2 to invade Matrigel. Increased invasiveness was also shown for HuH7 cells, but no scattering was observed and cell proliferation was stimulated. All the effects of MF on both tumor cell types were blocked by addition of an antibody to HGF and they all could be reproduced by adding recombinant HGF to the tumor cells. RT-PCR and Western blot analysis confirmed that both tumor cell lines expressed c-met, the receptor for HGF. The effects of MF-conditioned medium were not reproduced by acidic fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor (EGF), transforming growth factor-beta1 (TGF-beta1), or platelet-derived growth factor (PDGF-BB). Reverse transcription-polymerase chain reaction (RT-PCR) analysis confirmed that HGF was expressed in human HCC. Our data show that human liver MF act on HCC cells to increase their invasiveness and suggest that MF-derived HGF could be involved in the pathogenesis of HCC.

Human hepatic myofibroblasts increase invasiveness of hepatocellular carcinoma cells: evidence for a role of hepatocyte growth factor

The stroma of hepatocellular carcinomas (HCC) is infiltrated with myofibroblasts (MFs). Preliminary in vivo data have suggested that liver MF express hepatocyte growth factor (HGF), a cytokine that has been implicated in several tumor models. Our aim was to investigate the role of MF and HGF in HCC. Cultured liver MF expressed HGF messenger RNA (mRNA) and secreted HGF in their medium, as shown by Western blot, immunoprecipitation, and enzyme-linked immunosorbent assay (ELISA). Addition of MF-conditioned medium to the HepG2 HCC cell line induced cell scattering. This was associated with a decrease in cell proliferation. MF also increased about 100-fold the ability of HepG2 to invade Matrigel. Increased invasiveness was also shown for HuH7 cells, but no scattering was observed and cell proliferation was stimulated. All the effects of MF on both tumor cell types were blocked by addition of an antibody to HGF and they all could be reproduced by adding recombinant HGF to the tumor cells. RT-PCR and Western blot analysis confirmed that both tumor cell lines expressed c-met, the receptor for HGF. The effects of MF-conditioned medium were not reproduced by acidic fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor (EGF), transforming growth factor-beta1 (TGF-beta1), or platelet-derived growth factor (PDGF-BB). Reverse transcription-polymerase chain reaction (RT-PCR) analysis confirmed that HGF was expressed in human HCC. Our data show that human liver MF act on HCC cells to increase their invasiveness and suggest that MF-derived HGF could be involved in the pathogenesis of HCC.

Human hepatic myofibroblasts increase invasiveness of hepatocellular carcinoma cells: evidence for a role of hepatocyte growth factor

The stroma of hepatocellular carcinomas (HCC) is infiltrated with myofibroblasts (MFs). Preliminary in vivo data have suggested that liver MF express hepatocyte growth factor (HGF), a cytokine that has been implicated in several tumor models. Our aim was to investigate the role of MF and HGF in HCC. Cultured liver MF expressed HGF messenger RNA (mRNA) and secreted HGF in their medium, as shown by Western blot, immunoprecipitation, and enzyme-linked immunosorbent assay (ELISA). Addition of MF-conditioned medium to the HepG2 HCC cell line induced cell scattering. This was associated with a decrease in cell proliferation. MF also increased about 100-fold the ability of HepG2 to invade Matrigel. Increased invasiveness was also shown for HuH7 cells, but no scattering was observed and cell proliferation was stimulated. All the effects of MF on both tumor cell types were blocked by addition of an antibody to HGF and they all could be reproduced by adding recombinant HGF to the tumor cells. RT-PCR and Western blot analysis confirmed that both tumor cell lines expressed c-met, the receptor for HGF. The effects of MF-conditioned medium were not reproduced by acidic fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor (EGF), transforming growth factor-beta1 (TGF-beta1), or platelet-derived growth factor (PDGF-BB). Reverse transcription-polymerase chain reaction (RT-PCR) analysis confirmed that HGF was expressed in human HCC. Our data show that human liver MF act on HCC cells to increase their invasiveness and suggest that MF-derived HGF could be involved in the pathogenesis of HCC.

Prevalence of liver cell dysplasia and association with HCC in a series of 100 cirrhotic liver explants

BACKGROUND/AIMS

Liver cell dysplasia of large (LLCD) and small (SLCD) cell types may represent a premalignant change. We sought to evaluate their prevalence, relationship with the gross type of cirrhosis, aetiology of liver disease, and the presence of hepatocellular carcinoma in a series of cirrhotic livers.

METHODS

The presence and pattern of SLCD and LLCD were evaluated by careful histological analysis in 100 consecutive cirrhotic livers of viral (49%) or non viral (51%) aetiology, and with or without hepatocellular carcinoma. Prevalences were compared using Chi-square or Fisher's tests; relative risk for hepatocellular carcinoma was evaluated by the odds ratio.

RESULTS

Dysplasia was found in 82/100 of livers. Eighty-one had LLCD, with (n=49) or without (n=32) associated SLCD. SLCD alone was found in only one case. LLCD and SLCD tended to be more frequent and extensive in mixed or macronodular cirrhosis than in micronodular cirrhosis. LLCD was significantly more frequent and extensive in cirrhosis due to hepatitis B, as was SLCD in cirrhosis due to hepatitis B virus or biliary diseases, where it showed a different pattern (focal vs diffuse, respectively). LLCD and SLCD were both significantly associated with the presence of hepatocellular carcinoma, even of small size. Small foci of SLCD and widespread LLCD were the two conditions which showed the strongest association with hepatocellular carcinoma, with odds ratios of: 6.33 and 3.88, respectively. Widespread SLCD was not relevant for hepatocellular carcinoma in biliary diseases.

CONCLUSIONS

Liver cell dysplasia may be considered an additional risk factor for hepatocellular carcinoma in patients with cirrhosis and should be looked for in biopsies. Widespread LLCD and SLCD with a focal pattern are particularly relevant for hepatocellular carcinoma, whereas widespread small cell changes found in biliary diseases seem to have a different biological significance.

Characterization of a new human liver myofibroblast cell line: transcriptional regulation of plasminogen activator inhibitor type I by transforming growth factor beta 1

Myofibroblasts (MF) are a major effector cell type in liver fibrogenesis, where they are thought to derive from the activation of hepatic stellate cells. Cultured human MF, grown from liver explants, retain most of the in vivo characteristics of liver MF but are in limited supply. A continuous MF cell line would therefore be valuable in studying human liver fibrogenesis. For this purpose, we sought to immortalize human liver MF with polyoma virus large T antigen. MF were obtained from explants of human liver and transfected with a plasmid containing the coding sequence of polyoma virus large T antigen. This procedure yielded an activity growing cell line, designated GREF-X, which did not express large T antigen. Nevertheless, this cell line has been passaged repeatedly for almost 1 year and is thus likely immortalized. The morphology of GREF-X resembles that of primary liver MF. These cells have a doubling time of approximately 72 hours and are density-inhibited, and their growth is serum-dependent. Moreover, GREF-X cells do not grow in soft agar or induce tumors in nude mice, suggesting that they are not transformed. They stain positively for MF markers, such as smooth muscle alpha-actin and vimentin; express collagens type I, IV, V, and VI, fibronectin, and laminin: and secrete matrix-metalloproteinase-2. In addition, GREF-X cells are able to take up and esterify [3H]retinol, suggesting that they actually derive from hepatic stellate cells. Finally, these cells respond to transforming growth factor-beta 1, a major mediator of liver fibrogenesis, by increasing secretion of fibronectin and plasminogen activator-inhibitor type 1. Transient transfection experiments showed that plasminogen activator-inhibitor type 1 regulation, by transforming growth factor-beta 1, was transcriptional. We believe, therefore, that GREF-X would be a useful tool for studying the pathophysiology and pharmacology of liver fibrogenesis.

Extracellular matrix composition and integrin expression in early hepatocarcinogenesis in human cirrhotic liver

Extracellular matrix (ECM) plays a major role in cell differentiation, proliferation, and gene expression, both in physiological and in pathological conditions. Immunohistochemistry has been used to investigate modifications of ECM and related receptors, the integrins, in 26 small nodular lesions developed in human cirrhotic livers, on the basis that these lesions could represent sequential steps of hepatocarcinogenesis: the lesions were 16 macroregenerative nodules (MRNs), either of ordinary (n = 5) or atypical (n = 11) type, and ten small (< 15 mm) hepatocellular carcinomas (HCCs). Data were compared with those obtained in the surrounding cirrhotic tissue, in large HCCs, and in normal liver. The results indicate similarities between ordinary MRNs and cirrhosis, on the one hand, and between atypical MRNs and small HCCs, on the other. Strong and homogeneous deposition of collagen type IV and laminin in sinusoids and overexpression of alpha 6 integrin by sinusoidal cells and hepatocytes were especially noticeable in dysplastic areas characteristic of atypical MRNs, as in small HCCs. In addition, the staining of alpha 2 and alpha 6 integrins in MRNs revealed the presence of widespread atypical ductular proliferation expanding from periportal and perinodular areas, containing epithelial cells with transitional (hepato-biliary) phenotype. These findings suggest a transition from atypical MRNs to small HCCs and a possible role for liver epithelial precursor cells ('stem cells') in the development and evolution of MRNs.

Case report: incomplete septal cirrhosis with liver cell dysplasia

A 60-year-old woman was transplanted for end-stage alcoholic cirrhosis. The diagnosis of cirrhosis was made 13 years earlier on the basis of features of portal hypertension and a wedge liver biopsy. Liver function tests were subnormal except for a low prothrombin time. Unproven possible alcohol abuse was the only aetiological factor. Her condition remained unchanged until transplantation, despite complete abstinence. Histological examination of the explant showed incomplete septal cirrhosis associated with distal obstructive portal venopathy, cirrhotic nodules predominantly in the subcapsular areas and nodular regenerative hyperplasia with septal fibrosis elsewhere. In addition, there were areas of large and small liver cell dysplasia. This observation shows the difficulty in making a diagnosis of incomplete septal cirrhosis and the hypothetical link between liver cell dysplasia (which has never been reported in incomplete septal cirrhosis but is well known to be associated with hepatocellular carcinoma in cirrhosis) and rare cases of liver adenomas and carcinomas reported in patients presenting with liver vascular disorders.

Extracellular matrix composition and integrin expression in early hepatocarcinogenesis in human cirrhotic liver

Extracellular matrix (ECM) plays a major role in cell differentiation, proliferation, and gene expression, both in physiological and in pathological conditions. Immunohistochemistry has been used to investigate modifications of ECM and related receptors, the integrins, in 26 small nodular lesions developed in human cirrhotic livers, on the basis that these lesions could represent sequential steps of hepatocarcinogenesis: the lesions were 16 macroregenerative nodules (MRNs), either of ordinary (n = 5) or atypical (n = 11) type, and ten small (< 15 mm) hepatocellular carcinomas (HCCs). Data were compared with those obtained in the surrounding cirrhotic tissue, in large HCCs, and in normal liver. The results indicate similarities between ordinary MRNs and cirrhosis, on the one hand, and between atypical MRNs and small HCCs, on the other. Strong and homogeneous deposition of collagen type IV and laminin in sinusoids and overexpression of alpha 6 integrin by sinusoidal cells and hepatocytes were especially noticeable in dysplastic areas characteristic of atypical MRNs, as in small HCCs. In addition, the staining of alpha 2 and alpha 6 integrins in MRNs revealed the presence of widespread atypical ductular proliferation expanding from periportal and perinodular areas, containing epithelial cells with transitional (hepato-biliary) phenotype. These findings suggest a transition from atypical MRNs to small HCCs and a possible role for liver epithelial precursor cells ('stem cells') in the development and evolution of MRNs.

Human Kupffer cell recognition and phagocytosis of apoptotic peripheral blood lymphocytes

Cells undergoing apoptosis are recognized and rapidly phagocytosed by macrophages before their degradation, thus preventing the inflammatory reaction and protecting tissues from the damaging effects of released potentially harmful intracellular contents. In spite of growing interest in the mechanisms leading to the engulfment of apoptotic cells, the molecular bases by which an apoptotic cell is recognized are not entirely understood. Among the several potential mechanisms by which a macrophage can identify a cell as apoptotic, the data reported in the present paper support the idea that Kupffer cells phagocytose apoptotic cells by means of lectin-like receptors. Human Kupffer cells, which possess galactose-specific binding sites, can recognize and phagocytose peripheral blood lymphocytes undergoing apoptosis after heat shock (43 degrees C) or cycloheximide treatment, but not normal living peripheral blood lymphocytes. The putative structure by which apoptotic peripheral blood lymphocytes are targeted as "edible" could be the molecular changes in the plasma membrane, In fact, our experiments indicate that the membranes of apoptotic peripheral blood lymphocytes express increased amounts of N-acetylgalactosamine, D-galactose, and mannose residues when compared with membranes of normal PBL. Phagocytosis was inhibited by adding to the culture medium sugar cocktail solution (glucose, N-acetylgalactosamine, methyl mannopyranoside, fucose, 80 mM final concentration) or to a lower extent by desialylated glycoproteins (lactosylated bovine serum albumin, asialofetuin, 2 mg/ml final concentration), but not by nondesialylated glycoproteins (fetuin, 2 mg/ml final concentration, bovine serum albumin, 20% final concentration). In addition, phagocytosis of apoptotic peripheral blood lymphocytes by human Kupffer cells was a very rapid process, being almost entirely completed within 15 min of incubation.

Morphology of hepatic stellate cells in patients with fulminant or subfulminant hepatitis requiring liver transplantation

Hepatic stellate cells were studied by immuno-cytochemistry with anti smooth muscle alpha-actin antibody (an activation marker for these cells) and electron microscopy, in eleven patients transplanted for fulminant or subfulminant hepatitis. Numerous smooth muscle alpha-actin positive cells were found in necrotic areas. In both fulminant and subfulminant hepatitis, hepatic stellate cells appeared enlarged, often irregular, with spikes. There were numerous signs of activation and many contained numerous small lipid droplets. In the cases of fulminant hepatitis, hepatic stellate cells presented, at times, some subcellular damage. Hepatic stellate cells processes, often in several layers, displayed numerous cytoplasmic microfilaments with conspicuous dense plaques below the plasma membrane. Hepatic stellate cells were never surrounded by a basement membrane. The extracellular matrix was loose and granulofibrillar. In areas of multiacinar nodules (in cases of map-like pattern), hepatic stellate cells were grossly normal. These results are in agreement with in vitro data showing that acutely damaged hepatocytes activate hepatic stellate cells but do not fully transform them into myofibroblasts.

Human liver-associated lymphocytes: an overview

Morphological and phenotypical data indicate that liver sinusoids contain a heterogeneous population of lymphocytes of which large granular lymphocytes are only one element. It is suggested that the term of liver-associated lymphocytes (LAL), which encompasses all sinusoidal lymphocytes, be used for this fourth sinusoidal cell type. Studies realized by flow cytometry on isolated cells have shown that human LAL differ phenotypically from peripheral blood lymphocytes (PBL). LAL are characterized by a three-fold increase in the percentage of cells presenting the CD56 antigen, a natural killer (NK) marker, but also an increase in the percentage of CD8 cells and a decrease in the percentage of CD4. Furthermore, within the CD56+ LAL population, 95% of cells are CD3+/- CD16-, whereas the majority of CD56+ cells in PBL are CD3-/CD16+. These differences do not seem to depend on liver pathology since no differences were found in the LAL phenotype, for all markers analysed, between patients with liver metastasis or with benign liver tumours. Liver sinusoids also harbour T cells bearing the gamma/delta chains with a repertoire of V gene arrangements which differs from that found in PBL from the same patients, confirming a site-specificity. Functionally, LAL were shown to possess a higher level of NK cell activity against K-562 cells than PBL. LAL also expressed a lymphokine activated killer (LAK) activity against NK-resistant cell lines (Raji cells), whereas no such activity was detected in PBL from the same patients. Interestingly, LAK-activity from LAL isolated from patients with liver metastases was dramatically decreased compared to that from LAL isolated from patients with benign liver disease. The level of LAK activity of LAL situated distant to the malignant tumour was higher than that obtained from LAL close to the tumour, thus suggesting that cytotoxic lymphocyte capabilities could be inhibited by tumoral cells. LAL differ, both quantitatively and qualitatively, from PBL in the expression of cellular adhesion molecules. Precise mechanisms of their homing or in situ differentiation must still be elucidated.

[Frequency and severity of viral hepatitis C after liver transplantation. Study in 28 patients]

OBJECTIVES AND METHODS

HCV cirrhosis is one of the major indications for liver transplantation. HCV recurrence rate is high but long term development to cirrhosis seems to be rare. This study included 28 patients with HCV infection (HCV RNA in blood, histologic lesions highly suggestive or compatible with HCV infection).

RESULTS

Twenty-one out of the 28 patients were transplanted for hepatic chronic liver disease associated with HCV infection (reinfection), whereas only 7 out of 94 transplanted patients (7.4%) without pre-transplant HCV infection ("de novo" infection). Patients were followed clinically and histologically for a mean period of 26.8 months (range: 3-56). Of 26 patients with a good histological evaluation, 24 (92.3%) had chronic hepatitis: 7 with mild activity, 17 with moderate activity, 7 of whom had bridging fibrosis. Two patients had unusual features with associated lesions (necrotic hepatitis and chronic rejection in one case, acute hepatitis associated with CMV infection in the other).

CONCLUSION

This study confirms the high prevalence of HCV recurrence, as well as the "de novo" infection risk, and suggests caution concerning long term prognosis.

Adenomatous hyperplasia in cirrhotic livers: histological evaluation, cellular density, and proliferative activity of 35 macronodular lesions in the cirrhotic explants of 10 adult French patients

We examined 41 consecutive cirrhotic liver explants from French patients for the presence of nodules of adenomatous hyperplasia (AH) and then analyzed these lesions, together with underlying cirrhosis (C) and associated hepatocellular carcinoma (HCC), for various histological parameters, cellular density, and proliferative activity. Thirty-five AHs were identified in 10 livers (prevalence, 24%); seven of 10 were HCV positive. Hepatocellular carcinoma was more frequent in patients with AH than in patients without. The AHs consisted of 17 ordinary (OAH) and 18 atypical (AAH) adenomatous hyperplasia lesions. There was a malignant focus in five of the 18 AAHs. Wide areas of large liver cell dysplasia were frequent in OAH but never found in AAH. Obvious steatosis was frequent in HCC but exceptional in AAH and absent in OAH. There was a significant increase in cellular density in AAH and HCC as compared with C and OAH. Proliferative cell nuclear antigen immunostaining similarly showed an increase in proliferation from OAH or C to AAH and HCC. These data suggest that, in Europe as in Japan, one pathway of hepatocarcinogenesis is a multistep process in which AAH should be considered as a premalignant lesion very close to grade I HCC, while OAH seems to correspond to a regenerative nodule with limited proliferative ability.

Expression of cell adhesion molecules on liver-associated lymphocytes and their ligands on sinusoidal lining cells in patients with benign or malignant liver disease

Liver sinusoids, in contrast with the capillaries of other tissues, contain large numbers of sequestered lymphocytes. These blood-borne cells preferentially home in the liver. The mechanism regulating the recruitment of these cells and molecular regulation of the recognition of endothelial cells is as yet unclear. The present study sought to evaluate the cell adhesion molecules on human liver-associated lymphocytes and their ligands on sinusoidal lining cells in 29 patients undergoing partial hepatectomy for liver tumors. Liver-associated lymphocytes and peripheral blood lymphocytes were analyzed by flow cytometry using monoclonal antibodies. Frozen sections of liver tissue were stained according to alkaline phosphatase anti-alkaline phosphatase method. Cytometric analysis showed that virtually all liver-associated lymphocytes expressed on their surface the cell adhesion molecules LFA-1 and VLA-4. This liver-associated lymphocyte population also presented a significantly higher percentage of Mac 1, ICAM-1, and LFA-3 and an increased surface expression of LFA-1, LFA-2, and NCAM in comparison with peripheral blood lymphocytes. It was likewise shown that sinusoidal cells express ICAM-1, ICAM-2, ICAM-3, VCAM-1 and LFA-3 ligands. Liver-associated lymphocytes thus strongly express a number of different adhesion molecules. The corresponding ligands were also detected on sinusoidal lining cells. LFA-1 and VLA-4 would seem to be important pathways of temporary lymphocyte-endothelial adhesion in liver sinusoids.

Variations in the expression of cell-adhesion molecules on liver-associated lymphocytes and peripheral-blood lymphocytes in patients with and without liver metastasis

We evaluated the expression of the cell-adhesion molecules (CAM) that might be involved in liver-associated lymphocyte (LAL) contacts with other sinusoidal cells and/or be responsible for natural-killer(NK)- and lymphokine-activated killer(LAK) activity in patients with liver metastasis. The LAL population was isolated by sinusoidal high-pressure lavage from partial hepatectomies obtained from patients operated for metastases (n = 13) and benign liver tumors (n = 9). Surface expression of the beta-2-integrin chains (CD11a, CD11b, CD11c and CD18), and the beta-I-integrin chains (CD49b, CD49d, CD49f and CD29), as well as that of members of the immunoglobulin superfamily (CD2, CD54, CD56 and CD58), were analyzed by one- or two-color flow cytometry. Quantitative and qualitative differences were observed in both groups of patients in the expression of CAM between LAL and peripheral blood lymphocytes (PBL). LAL were characterized by an increase in the percentage of CD11b-, CD49b-, CD49d-, CD54-, CD56- and CD58-positive cells in comparison with PBL. Fluorescence values for CD2, CD11a, CD18 and CD56 were higher in LAL than in PBL. Moreover, the population expressing these antigens of differentiation presented a bimodal distribution (dim and bright): in LAL, as opposed to PBL, the percentage of cells with a bright phenotype was greater than of those with a dim one. The increase in CAM expression on LAL could be due to the influence of the liver sinusoidal micro-environment. Results were more unexpected for the comparison between benign and malignant tumors. No difference was found in CAM expression on LAL between these 2 categories. Consequently, it cannot be this factor that explains the decrease in LAK activity of LAL in patients with metastasis.