C Torresani

Università degli Studi di Brescia, Brescia, Lombardy, Italy

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Publications (34)96.31 Total impact

  • Contact Dermatitis 04/2006; 29(5):282 - 283. · 2.93 Impact Factor
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    ABSTRACT: Although dendritic cells (DC) are well known for their immunogenic capacities, they may even induce peripheral T-cell tolerance, and such a tolerogenic potential can be exerted in mouse through the expression on the DC plasma membrane of the CD95-ligand (CD95-L) molecule, which is able to trigger apoptosis of CD95-expressing antigen-specific T cells. We therefore asked whether epidermal DC, namely Langerhans' cells (LC), either resting (i.e. within the epidermis, 'in situ') or activated (i.e. suspended from the epidermis) or both, could express the CD95-L molecule on the plasma membrane. For such a purpose, two colloidal gold-immunoelectron microscopy (IEM) double-step procedures were carried out: an 'in situ' method, able to investigate resting LC, was performed on ultrathin frozen sections obtained by ultracryomicrotomy (UCMT) of normal skin biopsies; a pre-embedding (P-E) method, able to investigate suspended LC, was performed on epidermal cells (EC) suspended from normal skin specimens. In UCMT/IEM sections, resting LC showed gold particles within the cytoplasm but very rarely within organelles and never along the plasma membrane: resting LC are therefore capable of synthesizing CD95-L but not of expressing it in a functional location, thus autoreactive phenomena against CD95-expressing EC being avoided in normal epidermis. On the other hand, in P-E/IEM preparations, suspended LC showed several gold particles along the plasma membrane: activated LC are therefore capable of expressing CD95-L in a functional location, thus bearing the potential to exert tolerogenic capabilities against CD95-expressing T cells, e.g. to prevent inflammatory/autoimmune cutaneous disorders and/or favor the resolution thereof.
    Experimental Dermatology 11/2003; 12(5):692-9. · 3.58 Impact Factor
  • Contact Dermatitis 05/2003; 48(4):237-8. · 2.93 Impact Factor
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    ABSTRACT: Fas-L molecules expressed by in vitro stimulated T cells may be critically involved in suicidal activation-induced cell death (AICD) of such cells through engagement of their Fas receptors. A similar suicide of T cells was postulated to occur even in vivo, to eliminate dangerous activated lymphocytes; however, the demonstration of suicidal AICD of T cells in healthy humans in vivo is still lacking. We therefore investigated the possible occurrence of Fas-L-linked suicidal apoptosis of T cells in normal human peripheral blood. For this purpose, we took advantage of immunoelectron microscopy, which allows simultaneous visualization of the morphological apoptotic cellular changes together with surface expression of Fas-L molecules. Very few T lymphocytes were observed showing the ultrastructural features of apoptotic lymphocytes; these occasional apoptotic T cells, together with the majority of the normal T cell population, expressed the Fas molecule on the plasma membrane, as expected. Interestingly, the apoptotic cells were also Fas-L-positive, whereas normal T cells were Fas-L-negative. Such Fas-L-associated T cell suicide operating in vivo in healthy individuals is presumably able to suppress immune responses and prevent autoreactivity, thus maintaining the homeostasis of human blood.
    American Journal Of Pathology 03/2001; 158(2):387-91. · 4.52 Impact Factor
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    ABSTRACT: Fas-L molecules expressed by in vitro stimulated T cells may be critically involved in suicidal activation-induced cell death (AICD) of such cells through engagement of their Fas receptors. A similar suicide of T cells was postulated to occur even in vivo, to eliminate dangerous activated lymphocytes; however, the demonstration of suicidal AICD of T cells in healthy humans in vivo is still lacking. We therefore investigated the possible occurrence of Fas-L-linked suicidal apoptosis of T cells in normal human peripheral blood. For this purpose, we took advantage of immunoelectron microscopy, which allows simultaneous visualization of the morphological apoptotic cellular changes together with surface expression of Fas-L molecules. Very few T lymphocytes were observed showing the ultrastructural features of apoptotic lymphocytes; these occasional apoptotic T cells, together with the majority of the normal T cell population, expressed the Fas molecule on the plasma membrane, as expected. Interestingly, the apoptotic cells were also Fas-L-positive, whereas normal T cells were Fas-L-negative. Such Fas-L-associated T cell suicide operating in vivo in healthy individuals is presumably able to suppress immune responses and prevent autoreactivity, thus maintaining the homeostasis of human blood.
    American Journal of Pathology - AMER J PATHOL. 01/2001; 158(2):387-391.
  • British Journal of Dermatology 11/2000; 143(4):892-3. · 3.76 Impact Factor
  • C Torresani
    International Journal of Dermatology 06/1998; 37(5):347-9. · 1.34 Impact Factor
  • C Torresani, A Pavesi, G C Manara
    International Journal of Dermatology 01/1998; 36(12):942-6. · 1.34 Impact Factor
  • C Torresani, I Periti, L Beski
    Contact Dermatitis 10/1996; 35(3):174-5. · 2.93 Impact Factor
  • Clinical and Experimental Dermatology 12/1994; 19(6):535-6. · 1.33 Impact Factor
  • C Torresani, E Caprari, G C Manara
    Contact Dermatitis 12/1993; 29(5):282-3. · 2.93 Impact Factor
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    ABSTRACT: Thrombospondin (TSP) is an adhesive protein with multiple binding sites, which is able to mediate several cell-to-cell and cell-to-matrix interactions, particularly through its cell membrane receptor (TSP-R). Because human keratinocytes are able to synthesize and express TSP, and as TSP is also localized at the dermal-epidermal junction in normal human skin, we questioned whether epidermal cells are able to bind available TSP, that is, to express TSP-R. To investigate this, we employed gold immunoelectron microscopy on epidermal cells freshly isolated from normal human skin; the TSP-R was detected by OKM5 monoclonal antibody. Epidermal cells showing ultrastructural characteristics of melanocytes were gold-stained on their plasma membrane, whereas keratinocytes, Langerhans cells and lymphocytes were unstained. Although functional studies are clearly necessary to clarify the role(s) played by the TSP-R on the cell surface of melanocytes, it is tempting to speculate that the TSP-R may be important for melanocyte adhesion to the dermal-epidermal junction and to keratinocytes. Such adhesion may not only subserve the steric localization of melanocytes, but also have important implications for those functional activities of melanocytes which have been shown to require close contact between these cells and adjacent keratinocytes and/or basement membrane components.
    British Journal of Dermatology 09/1993; 129(2):131-7. · 3.76 Impact Factor
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    Journal of Investigative Dermatology 02/1992; 98(1):121-2. · 6.19 Impact Factor
  • C Torresani
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    ABSTRACT: In previous studies, IgE molecules were detected along the cell membrane of Langerhans cells (LC) in atopic dermatitis involved skin. However, the exact nature of the receptor still remains obscure. Moreover, large subsets of leukocytes have been recently shown to express the low affinity receptor for the Fc portion of IgE (Fc epsilon RII/CD23). Since LC are epidermal leukocytes the present study was intended in order to verify if LC of normal human subjects express the Fc epsilon RII/CD23. An anti-CD23 monoclonal antibody (MoAb) was used in a double step gold immunoelectron microscopical (IEM) procedure, carried out on Ficoll-Hypaque LC-enriched epidermal cell suspensions, freshly isolated from midly trypsinized normal human skin. Cells with LC features showed gold particles on their surface. Up to now LC from normal human epidermis, investigated using MoAb against human IgE, apparently were IgE-negative. Here we inequivocally demonstrate that the Fc epsilon RII/CD23 is constitutively expressed by normal human LC. It is well known that LC play an important role in antigen presentation. Further, it has been previously described the existence of a steric relationship between CD23 and HLA-DR molecules. Therefore, the present data add further strength to the hypothesis that FC epsilon RII/CD23 could participate to antigen presentation phenomena.
    Acta bio-medica: Atenei Parmensis 02/1992; 63(1-2):147-52.
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    ABSTRACT: Large subsets of leucocytes were recently shown to express the low affinity receptor for the Fc portion of IgE. Because Langerhans cells (LC) are epidermal leucocytes, we investigated whether LC of normal human subjects might express this receptor. Whereas conventional immunofluorescence on epidermal sheets gave negative results, highly sensitive immunoelectron microscopy revealed that a subset (about one-third) of freshly isolated LC express the CD23 molecule.
    British Journal of Dermatology 07/1991; 124(6):533-7. · 3.76 Impact Factor
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    ABSTRACT: It is now becoming clear that a collection of adhesion molecules is required on the surface of epidermal cells (EC) to establish the cell interactions that are necessary for skin immunologic reactions. In previous studies, we showed that human resting Langerhans cells (LC) express at least two members of the "integrins" family of adhesive molecules, as well as the intercellular adhesion molecule-1, which is a member of the immunoglobulin-related superfamily of molecules. This latter family includes another adhesive moiety, namely, the lymphocyte function-associated antigen-3 (LFA-3), which is the ligand for the T-lymphocyte-associated CD2 molecule, and has a broad tissue and organ distribution. In the present investigation the colloidal gold-immunoelectronmicroscopy immunostaining system and a quantitative analysis of the labeling provided decisive evidence for the weak but clear LFA-3 expression on virtually all keratinocytes (KC) and LC freshly isolated from normal human skin. Such constitutive expression of LFA-3 molecule on EC may be relevant for a number of functional interactions between LFA-3-positive EC and CD2-positive T lymphocytes within the cutaneous environment.
    Journal of Investigative Dermatology 05/1991; 96(4):512-7. · 6.19 Impact Factor
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    ABSTRACT: The potential of an immunogold-silver staining for the study of human suspended Langerhans cells at the transmission electron microscopic level was evaluated. Cells were labeled, by using a preembedding technique, with 5-nm colloidal gold particles followed by silver enhancement. The use of small colloidal gold particles permits a detection of small quantities of antigen; the metallic silver deposition around gold granules gives rise to a large electron-dense marker which can be easily detected even at low magnification. Ultrastructural details were well preserved, and the background was not significant. The major advantage of the present immunogold-silver staining is that it enables to detect labeled cells easily, even when limited amounts of antigenic moieties are present on a low percentage of cells. Therefore, a rapid and simultaneous evaluation of both immunophenotype and ultrastructural details of investigated cells is allowed.
    Dermatologica 02/1991; 182(4):221-4.
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    ABSTRACT: We examined morphometric as well as functional characteristics of CD16-positive human peripheral blood lymphocytes on the basis of the coexpression of the CD2 antigen. For morphometric analyses, nuclear area and cellular area were determined by counting line cross-points of a superimposed quadratic lattice test system overlying nuclei and the whole cell, respectively. Moreover, to evaluate the cellular villousity degree, the maximum inscrible circle and an irregular polygon were inscribed within cell profiles. The cytoplasm fraction included between the plasmalemma and the traced irregular polygon was considered as the villous portion of the cell. Finally, the NK capability was measured in a 6-hr 51Cr-release assay with human K-562 myeloid cells as targets. Within the CD16-positive cell population, the CD16-positive/CD2-negative cells seem to represent the most efficient NK cell subset. To the higher NK capability correspond a higher villousity degree and a lower nuclear area/cellular area ratio of the CD2-negative/CD16-positive subset, when compared with CD2-positive/CD16-positive cells.
    Cellular Immunology 07/1990; 128(1):118-29. · 1.74 Impact Factor
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    ABSTRACT: In recent years two cell populations with down-regulatory immune capabilities have been identified in murine epidermis. The present report demonstrates that even in human epidermis at least two populations of cells expressing suppressor-inducer phenotypes (i.e. CD45R-positive) exist, namely small subsets of keratinocytes and Langerhans' cells, respectively. Highly specific and sensitive 5-nm colloidal gold-immunoelectronmicroscopic techniques were carried out using anti-CD45R monoclonal antibodies, on freshly isolated crude epidermal cell suspensions, and 4000 cells were scrutinized in the electron microscope. Over 2% of the total epidermal cell population was CD45R+. Subpopulation analysis revealed that approximately 2% of keratinocytes and about 5% of the total Langerhans' cell population showed strong gold-plasma membrane staining, whilst the remaining epidermal cells were absolutely negative. Heterogeneity of staining together with this somehow surprising distribution of CD45R positivity on non-lymphoid epidermal cells was confirmed by the negative controls. These CD45R+ Langerhans' cells and keratinocytes are clearly candidates for the cells which have been functionally demonstrated as being capable of inducing down-regulation responsiveness in the human epidermis. However, functional investigations are needed to clarify the roles of the CD45R+ keratinocyte and Langerhans' cell subsets in the modulation of cutaneous immune responses.
    Immunology 05/1990; 69(4):622-5. · 3.71 Impact Factor
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    ABSTRACT: The intercellular adhesion molecule-1 (ICAM-1), which is a member of the immunoglobulin superfamily, is expressed on many cell types, including a variety of cells showing accessory/antigen-presenting capacities and belonging to the monocyte/macrophage or dendritic lineages. Here it is shown that human freshly isolated Langerhans cells (LC) constitutively express ICAM-1, as expected. It seems likely that the amounts of ICAM-1 moieties expressed on the plasma membrane of resting LC are only limited, since they virtually escaped detection by conventional immunofluorescence procedures on epidermal sheets. However, all the observed Birbeck granule-bearing LC showed their clear, although relatively weak, ICAM-1 positivity when more sensitive techniques were employed, such as colloidal gold-immunoelectronmicroscopy using gold particles 15nm in size and, to an even higher extent, using gold particles 5 nm in size. Because ICAM-1 is a ligand for the adhesive molecule LFA-1, which is expressed on the surface of leukocytes and, especially, lymphocytes, the ICAM-1 (LC)/LFA-1 (T-lymphocytes) interactions might, enabling these cells to adhere together, deliver activation signals to T cells, thus constituting the initial event in the generation of a cutaneous immune response.
    Journal of Investigative Dermatology 04/1990; 94(3):317-21. · 6.19 Impact Factor