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The expression of the selectin receptor LAM-1/Leu 8 was analysed in normal and in inflamed liver tissue, and its expression on mononuclear inflammatory cells was correlated with their topographical distribution in various compartments of the inflamed liver, in order to obtain new insights on possible molecular mechanisms involved in the traffic of mononuclear inflammatory cells throughout the diseased hepatic parenchyma. In normal liver tissue, few scattered mononuclear cells in portal and lobular parenchyma corresponded to both CD4+ and CD8+, as well as to CD45RA+ (2H4+) naive and CD45RO+ (UCHL1+) memory T cells, and were LAM-1/Leu 8+. In acute and chronic inflamed liver biopsies, CD45RO+ (UCHL1+) CD4+ and CD8+ memory T cells largely predominated in both portal and lobular parenchyma. The expression of LAM-1/Leu 8 antigen on these memory T cells varied according to their localization in the liver parenchyma, and it was not correlated with specific aetiological causes. In acute hepatitis, the vast majority of T lymphocytes were LAM-1/Leu 8-. In chronic active hepatitis, memory T cells in portal tracts expressed LAM-1/Leu 8, whereas virtually all intralobular T cells accumulating in areas of periportal and intralobular inflammation were LAM-1/Leu 8-. In chronic persistent hepatitis, the LAM-1/Leu 8+ T cells largely predominated among the numerous mononuclear inflammatory cells within enlarged portal tracts, whereas LAM-1/Leu 8- T cells were restricted to areas of intralobular 'spotty' inflammation. Therefore, two phenotypical populations can be recognized among the memory T cells in inflamed liver tissue, according to their topographical localization: LAM-1/Leu 8+ T cells predominating in portal tracts, and LAM-1/Leu 8- T cells predominating in the lobular parenchyma. These data show that during their migration through the inflamed liver parenchyma, memory T lymphocytes undergo phenotypical changes (LAM-1/Leu 8 shedding) according to their localization in different liver compartments (portal tracts vs. lobular parenchyma), suggesting multiple cellular and molecular mechanisms involved in the regulation of the leucocyte traffic through inflamed liver tissue.

We have examined the in-situ distribution of type A and type B receptors for tumor necrosis factor (TNF) in normal and diseased human liver biopsy specimens. In normal liver tissue, no or very small amounts of TNF receptors were found. In acute and chronic inflammatory liver diseases, a strong up-regulation of the expression of both TNF receptors was found on hepatocytes, bile duct epithelium, sinusoidal lining cells and mononuclear inflammatory cells. With immunoelectronmicroscopy, all these cells showed cytoplasmic, in addition to membranous staining, suggesting active synthesis of the receptor or, alternatively, internalization of the receptor and its ligand. This up-regulated expression of both type A and type B receptors for TNF was similar in acute and chronic active hepatitis, and was not related to the etiology of the liver disease, nor restricted to areas of liver inflammation. Our results indicate that hepatocytes, sinusoidal endothelial cells, bile duct epithelial cells and mononuclear inflammatory cells, by displaying receptors for TNFs, represent target cells for both these cytokines. Up-regulated expression of type A and type B receptors for TNFs endows these cells with augmented responsiveness for the pleiomorphic biological activities of these cytokines during liver injury.

Adhesion to and penetration through the sinusoidal vascular endothelium is a mandatory step for leukocyte migration and accumulation at sites of liver inflammation. This leukocyte trafficking is controlled by interactions between adhesion molecules on leukocytes and corresponding ligands on endothelial cells. We have analyzed the in situ distribution of two recently described vascular adhesion molecules (i.e., endothelial leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1) and of the lymphocyte "homing" receptor cluster of differentiation antigen-44 in normal and inflamed liver biopsy specimens. Endothelial leukocyte adhesion molecule-1 and vascular cell adhesion molecule-1 were absent from normal liver tissue, but they were strongly expressed on sinusoidal lining cells in inflammatory liver disease. Endothelial leukocyte adhesion molecule-1 expression predominated diffusely throughout the liver parenchyma in acute hepatitis; in contrast, vascular cell adhesion molecule-1 was mainly expressed in areas of periportal and intralobular inflammation in chronic active and persistent hepatitis. The "homing" receptor cluster of differentiation antigen-44 was weakly expressed on scattered mononuclear cells and on sinusoidal lining cells in normal liver tissue, but it was strongly up-regulated on mononuclear inflammatory cells and sinusoidal lining cells in acute and chronic hepatitis. In addition, reactivity for the cluster of differentiation antigen-44 was found on the membranes of variously sized clusters of hepatocytes in biopsy specimens with acute hepatitis. De novo or up-regulated expression of these adhesion molecules on sinusoidal lining cells in inflamed liver biopsy specimens indicates that these cells actively modulate their phenotype in response to environmental factors, thus playing a key role in the recruitment of leukocytes in acute and chronic liver inflammation.

The "very late activation" (VLA) subgroup of the integrin superfamily of adhesion molecules plays a central role in cell-cell and cell-matrix interactions. The six different VLA dimers known so far consist of a common beta subunit and a variable alpha (1 to 6) subunit. They serve as receptors for laminin, collagen, and fibronectin or function as adhesion molecules for leukocytes and are therefore of great significance in embryogenesis, growth and repair, and in leukocyte recirculation. The distribution of the common beta and the variable alpha chains of the VLA were studied in normal, inflammatory, and cholestatic liver biopsy samples. In normal liver tissue, vascular endothelia express alpha 1, 2, 3, 5, and 6; bile duct epithelium alpha 2, 3, 5, and 6; connective tissue stroma alpha 1 and 2; hepatocytes alpha 1 and 5; sinusoidal lining cells alpha 1, 2, and 5; and mononuclear cells alpha 4. Whereas bile ducts and vascular endothelia do not show relevant changes in alpha chain expression in liver diseases, hepatocytes de novo express membranous alpha 3 and 6 in inflammatory liver diseases. In view of the role of the VLA-3 and VLA-6 as laminin receptors, this finding is in line with the production of laminin in active liver disease. Moreover, de novo expression of "bile duct type" alpha 2, 3, and 6 on periportal hepatocytes in cholestatic liver disease likely illustrates a phenotypic switch of hepatocytes towards bile duct epithelium during cholestasis.

T cells can be divided into two main phenotypic subpopulations-i.e., the CD45RA-positive (2H4-positive) "naive" subset and the CD45RO-positive (UCHL1-positive) "memory" subset. In light of this recent functional reinterpretation of T-lymphocyte subpopulations, we reinvestigated the composition of the inflammatory infiltrate in liver biopsy specimens from patients with acute and chronic hepatitis. In normal liver, the few scattered mononuclear cells present in portal tracts and in the intralobular parenchyma consisted of both CD45RA-positive (2H4-positive) naive and CD45RO-positive (UCHL1-positive) memory T cells. In inflammatory liver diseases, portal tract and periportal and intralobular areas of inflammation consisted virtually only of CD45RO-positive (UCHL1-positive) memory T cells, which strongly expressed the CDw29 (4B4) antigen, and the adhesion molecules LFA-1, CD2, LFA-3, CD44 and VLA-4 and the activation marker human leukocyte antigen-DR. These results indicate that activated memory T cells represent the predominant subpopulation of lymphocytes in areas of liver inflammation. Memory T cells strongly express various homing receptors and adhesion molecules, which probably allow them to accumulate at inflammatory sites and to strengthen interaction with target cells. Furthermore, the increased number of memory T cells with enhanced interferon-gamma production in areas of liver inflammation may contribute to the maintenance and up-regulation of immune responses occurring in inflammatory liver diseases.

Cell-mediated immune reactions occurring in liver diseases involve infiltration of inflammatory cells into the hepatic parenchyma. Almost nothing is known about cellular and molecular mechanisms regulating this leukocyte traffic during the afferent and efferent arms of the hepatic immune response. This overview emphasizes that various liver parenchymal cells appear to participate actively in the development of the inflammatory response.

The concept of chronic hepatitis is very complex. There is no generally recognized definition and no agreement on the nomenclature. In more recent times a subdivision into chronic persisting (CPH) and chronic active (aggressive or progressive) hepatitis (cah) has been proposed. Morphologically CPH has a mononuclear inflammatory infiltration of the portal fields with preservation of the lobules. In positive hepatitis B CPH, orcein-positive milkglass-shaped hepatocytes and washed-out nuclei have recently been established by immunofluorescence. Periportal inflammation (piecemeal necrosis) is characteristic of CAH. Severe forms show hepatocytolysis and confluent necroses in addition. Since there is not always a sharp division between CPH and CAH, an unequivocal diagnosis of clinical, biochemical, serologic and immunological data is required.

Immune light and electron microscopic examinations were carried out to investigate the localization of HBcAg in biopsies from patients with persistent HBs antigenemia. In biopsies with severe intralobular inflammation HBcAg was mainly observed in the cytoplasm of hepatocytes in contrast to nuclear localization in specimens with less severe histological changes. Immune electron microscopic examination demonstrated two different appearances of HBcAg, according to whether it was or was not associated with core particles. In biopsies with more severe parenchymal damage, an increased amount of non-particulate HBcAg was observed in the cytoplasmic matrix; four such biopsies with intracytoplasmic HBcAg also revealed HBcAg on the plasma membrane of the hepatocytes. These findings support the concept that HBcAg may function as a viral target antigen for the immune response in type B hepatitis.

An ultrastructural study of the cytology of piecemeal necrosis in 12 liver biopsies from patients with chronic active (aggressive) hepatitis revealed a variety of cell types. This communication deals with two particular cell types, only observed in areas of severe piecemeal necrosis--interdigitating reticulum cells (IDRCs) and dendritic reticulum cells (DRCs). IDRCs are typical components of T-cell regions in lymphoid organs. Cells with the characteristics of IDRCs were found in severe piecemeal necrosis at the periphery of portal tracts and in periportal areas. This suggests that areas of periportal piecemeal necrosis are analogous to the T-cell regions of lymphoid organs during immune reactions. DRCs are typical components of B-cell regions in lymphoid organs. Cells with the characteristics of DRCs were found in the central parts of portal tracts with follicle-like aggregations of lymphocytes, as seen in some cases with pronounced piecemeal necrosis. This finding suggest that follicle-like lymphocytic aggregates in portal tracts are analogous to the B-cell regions of lymphoid organs during immune reactions. A mesenchymal origin of DRCs is suggested. The finding of IDRCs and DRCs in severe piecemeal necrosis emphasizes the fundamental similarity of immune reactions in the liver to those in lymphoid organs. These data are discussed in relation to immunological findings in chronic active hepatitis.

Immune electron microscopic examination of hepatitis delta delta-antigen (HDAg) was carried out on liver biopsies from seven patients with chronic type B hepatitis and delta-infection. HDAg was mainly found in the nucleus, but in some scattered hepatocytes it was found in the cytoplasm also, either in association with ribosomes or in the hyaloplasm. The association of HDAg with ribosomes may be the result of translation from delta-messenger RNA on the same ribosomes. In the nucleus, delta-antigen was present in the chromatin area as irregular granular structures, and there was staining of aggregates of 20 to 30-nm particulate structures, similar to those first described in non-A, non-B hepatitis. However, similar particulate structures were also present in HDAg negative nuclei. The delta-particles which have been described in blood could not be identified in hepatocytes.

ABSTRACT- The predictive value of piecemeal necrosis (PMN) in acute hepatitis was investigated in 62 patients (39 hepatitis B virus infection, 9 hepatitis A virus infection and 14 possible hepatitis NANB virus infection). The 62 initial biopsies were blindly recoded and classified into three groups: 1. Acute hepatitis with signs of possible transition to chronicity (AHTC) (n = 35)(i.e. a picture of acute hepatitis associated with PMN). 2. AHTC-borderline group (BL) (n = 15) (i.e. a picture of acute hepatitis with minimal PMN). 3. Uncomplicated acute hepatitis (AH) (n = 12) (i.e. a picture of acute hepatitis without PMN). Follow-up of the patients revealed an evolution to chronicity in a very high percentage of the AHTC-cases of hepatitis B (95%) and NANB (89%) etiology. Also 67% of the BL-cases of hepatitis B etiology developed chronic liver disease. In hepatitis B the immunohistochemical pattern of HBsAg is of additional help. In hepatitis A, PMN is often present (5/9) but no evolution to chronicity was observed. This study shows that PMN in acute hepatitis appears to be a useful prognostic feature for chronicity in hepatitis B and NANB. [ABSTRACT FROM AUTHOR]

ABSTRACT- A new ultrastructural cytoplasmic marker designated as type 2, and distinct from type 1 previously associated with NA-NB hepatitis in chimpanzees, was found in hepatocytes of two patients and of one experimentally infected chimpanzee. These cases represent a minority of all cases we studied as presumed NA-NB viral hepatitis. Type 2 marker consists of tubular structures composed of an assembly of ring-like units coated with smaller uniform fragments, accumulated in different patterns in dilated cisternae of the endoplasmic reticulum. Preliminary data using immunofluorescence with NA-NB hepatitis convalescent serum and antiserum against fibrinogen are reported. Type 2 marker may represent a different agent or a different reaction pattern to one agent of NA-NB viral hepatitis. Its features are compared with those of hepatitis B. [ABSTRACT FROM AUTHOR]

ABSTRACT- Ultrastructural investigation of liver biopsies from two patients with non-A, non-B hepatitis revealed cytoplasmic and nuclear alterations in the hepatocytes. The lesions in both patients, one with acute and one with chronic hepatitis, were similar and distinct from those previously described in other forms of hepatitis. These findings are compared with the reported findings in chimpanzee liver after inoculation with non-A, non-B infective material. The intranuclear findings are similar to the aggregations of 20-27 nm particles described in some infected chimpanzees, and the cytoplasmic alterations seem to be similar to the cytoplasmic structures and tubular arrangements reported in other inoculated chimpanzees. A striking finding of this study is the presence of both alterations together in the same biopsy in two different patients, suggesting that they represent a different stage of viral infection or different parts of the viral agent. It still remains to be proved that the ultrastructural particles indeed contain antigen(s) of the non-A, non-B hepatitis virus. The nuclear and cytoplasmic alterations are, however, characteristic for non-A, non-B hepatitis and are useful as ultrastructural hallmarks of this form of hepatitis. [ABSTRACT FROM AUTHOR]

ABSTRACT- We present the case of a female patient in whom acute hepatitis developed after 180 days of ketoconazole administration (200 mg/day). A prompt renewed hepatic injury after an unintentional rechallenge 6 months later provided definitive evidence for a causative relationship between ketoconazole and acute liver disease. The clinical and biochemical parameters of the case are reported. Histological examination revealed the picture of acute hepatitis with possible transition to chronicity. A prominent accumulation of perisinusoidal lipocytes (Ito cells) was observed. [ABSTRACT FROM AUTHOR]