Phorbol 12-myristate 13-acetate induces resistance of human melanoma cells to natural-killer-and lymphokine-activated-killer-mediated cytotoxicity

Summary Human melanoma cells are sensitive to the lytic activity of natural killer (NK) and lymphokine-activated killer (LAK) cells in vitro. The events resulting in tumour cell killing by lymphocytic effectors have not been completely clarified, and the same target cell determinants regulating responsiveness to immune cytolysis have not yet been identified. Indeed, changes in the differentiative status of leukemia cells as well as in the expression of major histocompatibility complex (MHC) antigens have been described to modulate sensitivity to cytotoxic effectors; moreover surface expression of adhesion factors or extracellular matrix proteins by the cancer cells can promote the activation of the cytolytic effectors and has been described to correlate with tumour cell sensitivity to cytolytic cells. We reasoned that treatment with differentiation inducers could modulate melanoma cell sensitivity to NK and LAK cells. The present study demonstrates that human melanoma GLL-19 cells, when treated with the phorbol diester phorbol 12-myristate 13-acetate (PMA) in vitro, undergo growth inhibition and neuron-like differentiation. Moreover PMA treatment induces an evident inhibition of GLL-19 cell sensitivity to NK- and LAK-mediated cytotoxicity. GLL-19 cells express constitutively MHC class I antigens. PMA treatment, however, does not modify the expression of MHC class I and class II DR antigens in human melanoma GLL-19 cells. We have finally evaluated the effects of PMA on the expression at the cell surface of adhesion factors such as ICAM-1, and extracellular matrix proteins such as collagen IV, laminin and fibronectin; we have also studied the expression of the integrin vitronectin receptor, a membrane receptor for adhesive proteins. While adhesion factors and extracellular matrix proteins appear to play an important role in the interaction between immune effector and tumour target, it can be supposed that the modulation of such membrane-associated proteins or glycoproteins induces NK and LAK resistance in cancer cells. We indeed found that PMA treatment induced in GLL-19 a marked reduction of membrane expression of collagen IV and ICAM-1; moreover PMA reduced the cell membrane expression of the integrin vitronectin receptor. On the other hand, membrane expression of fibronectin and laminin was not affected by PMA. These data indicate that the acquisition of a NK- and LAK-resistant phenotype by GLL-19 cells occurs together with cell differentiation, down-regulation of membrane expression of collagen IV, ICAM-1 and vitronectin receptor, but in the absence of changes in MHC antigens.This work has been supported by the Italian Association for Cancer Research (A. I. R. C.) and by Istituto Superiore di Sanità, Italy-USA joint program on New Therapies on Neoplasia.     

Incidence of sensitisation to the pollens of urticaceae (Parietaria), Poaceae and Oleaceae (Olea europea) and pollen rain in Liguria (Italy)

Summary The authors examined 734 sensitised patients living in four localities in Liguria (Genoa, Savona, Pietra Ligure and Sanremo). The commonest source of sensitisation (62.7%) was Urticaceae (Parietaria), followed by Poaceae (52.5%) andOlea europaea L. (24.0%). A survey of airborne pollens revealed a greater presence of Urticaceae and Poaceae in Genoa and of Oleaceae in Pietra Ligure and Sanremo.     

Storage mites sensitivity and allergic respiratory disease

Summary In order to evaluate the frequency of skin sensitivity to Storage Mites and the role of such sensitization in respiratory allergic disease in workers with occupational exposure to stored items we studied 217 dock workers, 93 farmers and 104 white collars.From the results of skin prick tests the sensitization to sole Storage Mites appears significantly higher among people working in docks or farms, compared with a control group. This confirms the role of the working environment in inducing sensitization to Storage Mites. Rhinitis and asthma however affect nearly always (27/29 cases) people with an associated sensitization to House Dust Mites. Further studies are needed to define the allergenic importance of Storage Mites in working environments.     

Multiple variants in subtelomeric regions of normal karyotypes

We describe a human genomic cosmid clone, 56.1.1, that contains subtelomeric sequences present on multiple human chromosomes. In particular, using fluorescence in situ hybridization, we have identified 16 sites of hybridization on 12 chromosomes. In a sample of 8 unrelated individuals, 10 of these sites showed interindividual variation. Co-hybridization with other polymorphic probes allowed us to demonstrate cytologically heterozygosity at three sites in six individuals. The chromosomal distribution of hybridization sites in a family strongly suggests that these variants are inherited in a Mendelian fashion. These data show that subtelomeric repeats are a rich source of genetic variability. Possible mechanisms of generation of such variants are discussed.     

Minor components in food plants--Note I. Flavonol glycosides from Ullucus tuberosus.

This work deals with the isolation and characterization in Ullucus tuberosus of flavonoids, a class of natural products influencing potentially the taste and nutritional value of the plant food. The three flavonoids, rutin, narcissin and kaempferol 3-O-(2",6"-di-O-alpha-L-rhamnopyranosil)-beta-D-glucopyranoside, isolated, are devoid of taste, but appear to possess health promoting effects.     

Ultrastructural analysis of asialoglycoprotein receptor mediated endocytosis in cultured newborn hepatocytes

We examined the receptor-mediated endocytosis of asialoglycoproteins in thick sections of cultured hepatocytes of newborn rats by high voltage electron microscope. The organelles involved in endocytosis are revealed ultrastructurally using colloidal gold particles coupled to lactosylated bovine serum albumin. Keeping the cells at 4 degrees C the marker binds to the cell surface showing microvilli, and is not internalized. Increasing the temperature to 37 degrees C, we observed that within 5-15 min. the marker enters the intracellular endocytic organelles close to the cell surface. After 60 min. the marker is found in the larger and deeper endocytic organelles and in large lisosome-like vesicles. We find that the process of endocytosis in newborn cultured hepatocytes is similar to that found in cultured cells of adult rats, but the process of internalization is slower.     

The role of NADPH in the regulation of glucose-6-phosphate and 6-phosphogluconate dehydrogenases in rat adipose tissue

Summary Previous studies examining the regulation of the synthesis of G6PDH and 6PGDH in rat liver and adipose tissue have focused on the induction of these enzymes by different diets and some hormones. In rat liver these enzymatic activities seem to be regulated by a mechanism involving changes in the NADPH requirements. In this paper we have studied the effect of changes in the flux through different NADPH-consuming pathways on G6PDH and 6PGDH levels in adipose tissue and on the NADPH/NADP ratio. The results show that: I) an increase in the consumption of NADPH, caused by the activation of either fatty acid synthesis or detoxification systems which consume NADPH, is paralleled by an increase in the levels of these enzymes; II) when the increase in consumption of NADPH is prevented, the G6PDH and 6PGDH levels do not change.Abbreviations G6PDH Glucose-6-Phosphate Dehydrogenase - 6PGDH 6-Phosphogluconate Dehydrogenase - GR Glutathione Reductase - ME Malic Enzyme - tBHP t-Butyl Hydroperoxide - NF Nitrofurantoin - CumOOH Cumene Hydroperoxide     

Elutriation of human keratinocytes and melanocytes fromin vitro cultured epithelium

Summary Human epidermal keratinocytes grown in culture and at different stages of differentiation are shown to be viably separated by elutriation. A specific fraction enriched in melanocytes was obtained. Elutriation of cells obtained fromin vitro cultured epithlium could prove useful in studies concerning the biochemistry and molecular markers of cells isolated from normal epithelium and from different pathologies.