Human epidermal keratinocytes are induced to secrete interleukin-6 and co-stimulate T lymphocyte proliferation by a CD40-dependent mechanism

Although the expression and function of CD40 on B lymphocytes has been well studied, the significance of CD40 on non-lymphoid cells such as keratinocytes (KC) is not as well characterized. We demonstrate in this report that CD40 is expressed by virtually all human KC, and that it functions as an important signaling molecule. Flow cytometry of undifferentiated and terminally differentiated KC indicated that both cell types expressed CD40, as determined by binding to monoclonal antibodies and a recombinant CD40 ligand fusion protein; interferon-gamma (IFN-gamma) treatment of KC increased CD40 expression. Cultured KC also expressed 1.5-kb CD40 transcripts. Activation of KC cell surface CD40 using the monoclonal antibody G28.5 resulted in the rapid generation of a 50-kDa tyrosine phosphorylated polypeptide, as well as a dose-dependent increase in the secretion of interleukin-6, a cytokine that has been linked to KC proliferation. KC also co-stimulated a significant T lymphocyte proliferative response to the mitogen phytohemagglutinin that was CD40 dependent. These data indicate that KC constitutively express a low level of functional CD40 and regulate their expression in response to IFN-gamma. These data support the concept that KC, via their expression of CD40, have the capacity to amplify inflammation in the skin by interacting with CD40 ligand-bearing T cells.

Bile acids in the assessment of hepatocellular function

Bile acids, which are synthesized in the liver from cholesterol, are important in the production of bile flow, excretion of cholesterol, and intestinal digestion and absorption of fats and fat-soluble vitamins. Increases and/or alterations in concentrations of bile acids in serum are specific and sensitive indicators of hepatobiliary disorders. Synthesis of bile acids in hepatocytes involves steps in endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. Other important hepatocellular processes involving bile acids include active uptake by the basolateral membrane, intracellular transport, P-450-mediated conjugations and hydroxylations, and canalicular secretion. Hydrophobic bile acids produce hepatotoxicity in vivo and in vitro. In experimental and epidemiologic studies, some of these forms have been identified as causative agents in the development of colon and liver (experimental only) cancer. Conversely, several hydrophilic forms, primarily ursodeoxycholic acid, have demonstrated cytoprotective properties in a variety of clinical and experimental hepatobiliary diseases and disorders. Because bile acids can have dramatically different properties and effects, determination of mechanisms of action of these compounds has become an active area of research. Primary isolated hepatocytes provide an opportunity to investigate bile acid-related functions and effects in well-designed, carefully controlled studies. Short-term cultures have been used to study a variety of issues related to bile acids, including cytotoxicity, synthesis, and hepatocellular processing. With these systems, however, many functions of mature hepatocytes, including those pertaining to bile acids, can be lost when cultures are maintained for more than several days. Recent developments in culture techniques permit long-term maintenance of functionally stable, differentiated cells. Pertaining to bile acid research, these systems remain to be fully characterized but, in appropriate situations, they should provide important alternatives to in vivo studies and short-term in vitro assays.

Undifferentiated nasopharyngeal cancer (UCNT): current diagnostic and therapeutic aspects

Undifferentiated carcinoma of the nasopharynx (UCNT) is a particular head and neck epidermoid lineage tumor related to the Epstein Barr Virus (EBV). It has geographically selective endemic epidemiologic features, without relation to external carcinogens. Its systemic agressiveness is the source of most disease-related demises, because radiotherapy achieves excellent local control and a significant percentage of cure in patients with exclusive locoregional disease. Difference in the staying systems currently in use, the recent changes in imaging and radiotherapy technology, and the lack of distinction between UCNT and squamous cell carcinoma (SCC) of the nasopharynx in Western literature reports make for some difficulty in therapeutic results evaluation when analyzing available literature. Its chemosensitivity is a relatively recent acknowledged fact, and its use in metastatic patients results in a high percentage of objective responses, many of long duration. Neoadjuvant cisplatin-based chemotherapy seems to be of benefit, but outstanding controversies in this regard will be soon answered through ongoing phase III trials. After a review of the current literature of all the above-mentioned aspects of this fascinating nosologic entity, our own experience, both in metastatic and locoregional disease patients is analyzed.

The association between carcinoma of the tonsil and Epstein-Barr virus--a study using radiolabelled in situ hybridization

We reviewed 30 cases of carcinoma of the tonsil and classified them as squamous cell carcinoma, non-keratinizing differentiated carcinoma and non-keratinizing undifferentiated carcinoma. Five cases of non-keratinizing undifferentiated carcinoma were identified, and these, together with 5 cases of squamous cell carcinoma, were studied for the presence of Epstein-Barr virus by in situ hybridization using early RNA (EBERs) as probes. All cases of squamous cell carcinoma were negative for EBER and only one of the 5 cases of non-keratinizing undifferentiated carcinoma was positive. As a positive control we used a case of a primary nasopharyngeal carcinoma with extension to the tonsil. Though the tonsil and nasopharynx share similar anatomical and immunological features, we conclude that in the majority of cases EBV is not demonstrable in tonsillar carcinomas.

Epstein-Barr virus infection, salted fish and nasopharyngeal carcinoma. A case-control study in southern China

Two hundred and five histologically confirmed cases of nasopharyngeal carcinoma (NPC) in southern China, and an equal number of matched controls, were investigated for their dietary habits, occupational exposure, use of tobacco and alcohol, history of relatives with NPC, and IgA against Epstein-Barr virus (EBV) capsid antigen (IgA/VCA). Positive IgA/VCA and intake of salted fish were associated with a strong excess risk of NPC. The association persisted after adjustment for other factors. The combination of salted fish and EBV was strongly associated with NPC, and more so than EBV or salted fish per se. Multivariate analyses showed that IgA/VCA was the most important predictor of NPC, and salted fish the second most important. These results suggest that EBV has a strong effect on the development of NPC. The exclusion of EBV and genetic factors in earlier epidemiological studies may have resulted in an overestimation of salted fish as important etiological factor causing NPC.

Infiltrating lymphocytes and accessory cells in nasopharyngeal carcinoma

The infiltrating lymphocytes (LCs) and accessory cells (ACs) including dendritic cells (DCs) and monocytes/macrophages in nasopharyngeal biopsies taken from 4 groups of nasopharyngeal carcinoma (NPC) patients were observed by using an immunostaining technique and the correlation of the results to the clinical manifestations and follow-up data was examined. The findings were as follows. (1) NPCs without lymph node metastasis always had marked infiltrating LCs and DCs as compared with those with lymph node(s) metastasis. (2) Advanced NPCs with lymph node(s) involvement (T1-4N1-3M0) and a rapid development of distant metastasis followed by death within 1 year after radiotherapy always showed fewer infiltrating LCs and DCs as compared with those with lymph node(s) metastasis (T1-4N1-3M0) and having longer than 5-year survival after radiotherapy. The amount of both LCs and ACs, especially DCs, infiltrating in NPC tissues appears to be an indicator of the activity of host immune defence mechanisms against cancer and influences the progression of the neoplasm as well as the prognosis.

Emergence of non-major-histocompatibility-complex-restricted lytic CD8+ cells in the blood of nasopharyngeal carcinoma patients

A large body of evidence has suggested that the Epstein-Barr virus (EBV) is strongly associated with undifferentiated nasopharyngeal carcinoma. Immunologically, this neoplasia is characterized by the absence of anti-EBV circulating cytotoxic T lymphocytes (CTL), despite a high number of peripheral activated CD8+ cells, as previously determined in our laboratory. In order to determine whether the absence of anti-EBV CTL is related to a reduced number of circulating anti-EBV effector cells, we attempted to expand these hypothetical specific T cells by induction of proliferation with recombinant interleukin-2 (rIL-2), in the, absence of any stimulator cells. Optimal conditions for stimulation of peripheral blood lymphocytes (PBL) of nasopharyngeal patients were obtained with 100 U/ml rIL-2 during 10 days of culture. PBL treated with rIL-2 induced a selective expansion of CD8+ cells and generated a potent cytotoxicity towards autologous or HLA-compatible lymphoblastoid cell lines, used as target cells in a chromium-release thest. However, this cytolysis was non-MHC-restricted, since, the monoclonal antibodies anti-(HLA class I) and anti-(HLA class II) were inefficient in inhibiting this cytotoxicity. Interestingly, purified CD8+ cells acquired the capacity for non-MHC-restricted cytolysis.

Epstein-Barr virus carriage by nasopharyngeal carcinoma in situ

We studied the distribution of the EBV genome in tumour biopsies obtained from 42 patients with poorly differentiated or undifferentiated nasopharyngeal carcinoma (NPC) and 3 patients with well-differentiated NPC. Six carcinoma in situ (CIS) foci were seen in 5 tumour specimens. By in-situ hybridization, multiple copies of the EBV genome were detected in some of the tumour cells in 3 CIS lesions involving the full thickness of the mucosal epithelium, but without microinvasion, while the viral genome was present in the majority of the tumour cells contained in another 3 CIS lesions with microinvasion. In agreement with previous findings, poorly differentiated and undifferentiated carcinomas regularly carried the viral genome, the number of copies of which was similar to that seen in CIS, while some, but not all, of the tumour cells of the well-differentiated histological type carried the virus. The viral genome was otherwise rarely detected in other areas of the mucosal epithelium and, where present, the viral carriage was confined to a few epithelial cells, in which the viral genome contents were markedly lower than in tumour cells. These results suggest that EBV may first become associated with NPC at an early stage of the disease shortly after the tumour has been initiated.