PubMed Health⌕ Search

Biomedical subjects

M Heslan

Publications and source records attributed to M Heslan.

14 recordsLinked to original sources
PubMed1990

Production of paf-acether by human epidermal cells.

The production of the inflammatory mediator paf-acether (paf) from human epidermal cells was investigated in vitro. Human epidermal cells, freshly isolated from normal skin or in culture, were incubated in Tyrode's buffer containing 0.25% lipid-free bovine serum albumin in the presence of 2 microM calcium ionophore A23187, at 37 degrees C, for 1 to 60 min. Paf production slightly began at the first min of stimulation, was significant after 10 min, reached a maximum at 20 min (251 +/- 25 pg/l X 10(6) cells, mean +/- 1 SD), and decreased thereafter. About 50% of the paf amount produced by epidermal cells was recovered in supernatants. Addition of the non-acetylated paf precursor 1-O-octadecyl-sn-glycero-3-phosphocholine, i.e., lyso-paf, at 0.1 microM to epidermal cells during A23187-stimulation did not alter this production. In contrast, addition of acetyl-coenzyme A at 0.1 mM enhanced paf production by 5 times. The material produced by epidermal cells was identical to synthetic paf because: 1) the aggregation of aspirin-treated and ADP-insensitive washed rabbit platelets it induced was inhibited by BN 52021, an antagonist of the paf putative receptor; 2) the factor was inactivated by phospholipase A2 but was insensitive to lipase from Rhizopus arrhizus; 3) it exhibited the same retention time as synthetic paf during standard and reverse-phase (RP) high-pressure liquid chromatography (HPLC) elution. The paf precursors, i.e., lyso-paf and 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine, were also detected in epidermal cells, stimulated with A23187 or not. As determined by RP-HPLC analysis and confirmed by gas chromatography analysis, these precursors and the paf produced by epidermal cells exhibited more than 90% of a hexadecyl chain at the sn-1 position of the molecule. The present results demonstrate the synthesis and release of paf by normal human epidermal cells. Paf production within the epidermis might account for the development of cutaneous inflammation and the pathogenesis of many skin disorders.

Acetyl Coenzyme A↗
PubMed1990

T-cell receptor-gamma/delta bearing lymphocytes in normal and inflammatory human skin.

Murine dendritic epidermal T cells (DETC) were recently reported to express T-cell receptor (TCR)-gamma/delta chains. In a search for the human equivalent of these cells, we tested normal and lesional skin with MoAb which react with the TCR-gamma/delta heterodimer. We performed indirect immunofluorescence (IF) on epidermal sheets, and alkaline-phosphatase-anti-alkaline-phosphatase complex (APAAP) on epidermal cell smears. Frozen skin sections from normal skin and various cutaneous lymphocyte infiltrates were also studied. A few CD3+ T lymphocytes were consistently found in normal epidermis. Most of these cells appeared to be TCR-alpha/beta +, and some CD4+ or CD8+. On epidermal sheets and cell smears, only a very small TCR-gamma/delta + cell population was visualized (less than 0.1% of the total). On normal skin sections, we observed 0 to 3 gamma/delta + cells per section. When present, they were often located in the epidermal basal layer, and were round or dendritic. Double immunolabeling revealed that gamma/delta + cells differed from CD1+ Langerhans cells, and that they had a similar phenotypic pattern as gamma/delta + peripheral lymphocytes (PBL): CD2+, CD3+, CD4-, and CD8-. Immunostaining from various inflammatory skin lesions showed that the dermal infiltrates included CD3+ T lymphocytes but virtually no gamma/delta + cells. Only a few gamma/delta + cells were found in some end-evolutive infiltrates. Taken together, these results strongly suggest that normal human epidermis occasionally harbors TCR-gamma/delta complex bearing lymphocytes, which constitute a small fraction of the CD3+ cutaneous T lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1989

[Mixed lympho-epidermal cell cultures: value in bone marrow grafts].

Graft-versus-host disease (GVHD) is the major complication of allogeneic HLA-identical bone marrow transplantation. GVHD is induced by the activation of mature T cells in the graft which react against minor antigens of the recipient. Mixed epidermal cell-lymphocyte cultures (MELC), which constitute an in vitro model of epidermal cell-lymphocyte interactions, make it possible to study the presentation of antigens to the lymphoid cells by epidermal Langerhans cells. We performed MELC in 66 patients who had received an HLA-identical bone marrow transplant for malignant blood disease. The bone marrow received by 29 recipients had been depleted of mature T cells, whereas 37 recipients had received a non-depleted bone marrow. A complete, uni- and multivariate statistical analysis was carried out on recipients of non-depleted bone marrow to evaluate the risk factors for acute and chronic GVHD. This study showed that MELC between donor and recipient was the most predictive parameter for the occurrence of GVHD. Other factors were a history of previous pregnancies in female donors and a diagnosis of chronic myelogenous leukaemia. These results may be of value in the selection of donors and for a better determination of the need for bone marrow depletion.

Animals↗
PubMed1989

Synthetic retinoids inhibit the antigen presenting properties of epidermal cells in vitro.

The clinical efficacy of retinoids in benign and malignant skin diseases involving immune mechanisms suggests that they affect the immunologic functions of the epidermis. However, these effects have yet to be demonstrated. The action of vitamin A (retinol) and the synthetic retinoids, isotretinoin, etretinate, acitretin, and arotinoid-free acid have been studied on the lymphocyte proliferation induced by phytohemagglutinin (PHA), by the mixed lymphocyte reaction (MLR), and the mixed epidermal cell-lymphocyte reaction (MECLR). The results for PHA-induced proliferations were highly variable for all the retinoids. However, in MECLR, the synthetic retinoids consistently reduced the proliferation by 20%-30%. This occurred at therapeutic drug concentrations of about 10(-7)M. In MLR, a minor decrease of 10%-15% was only found for higher concentrations (10(-5)M). Retinol induced no effect in either reaction. Further analysis of acitretin on MECLR showed that it reduced lymphocyte proliferation in a dose-dependent fashion. This reduction was combined with a decrease in cytotoxic T-lymphocyte induction (CTL). Addition of 10(-6)M acitretin at various times also revealed that its presence at cell culture initiation was necessary to inhibit proliferation significantly. Furthermore, cell treatments prior to MECLR showed that exposure of epidermal cells to acitretin was essential to produce this inhibition, suggesting that it acts directly on epidermal cells. Consequently, it is suggested that the specific inhibitory effect of synthetic retinoids on lymphocyte activation in MECLR may partly account for their therapeutic action on the skin.

Acitretin↗
PubMed1988

Cantharide acantholysis: endogenous protease activation leading to desmosomal plaque dissolution.

Using a method which allowed us to study the morphological consequences of the expression and the inhibition of proteases in living tissues, we demonstrated that the primary detectable cellular event in cantharide acantholysis is the dissolution of the dense plaque, leading to the detachment of tonofilaments from desmosomes. This process is inhibited by neutral serine protease inhibitors. This suggests that the desmosome-tonofilament complex, more precisely the desmosomal dense plaque, is the primary target of activated proteases during cantharide acantholysis, and can be disrupted by a specific epidermal protease-anti protease system. Cantharide acantholysis may be useful model for studying desmosomal turnover.

Acantholysis↗
PubMed1988

The mixed epidermal cell lymphocyte-reaction is the most predictive factor of acute graft-versus-host disease in bone marrow graft recipients.

Risk factors for acute graft-versus-host disease (GvHD) remain controversial. We performed uni- and multivariate statistical analyses on a series of 37 patients receiving a non-depleted allogeneic bone marrow transplant from an HLA-identical sibling donor for a haematological malignancy, in order to identify risk factors for GvHD. Three factors were associated with development of moderate to severe GvHD: a positive mixed epidermal cell-lymphocyte reaction (MECLR) between donor and recipient, previous pregnancies in female donors and chronic myeloid leukaemia diagnosis. The MECLR was the most important predictive factor, selected in first rank by the stepwise linear discriminant analysis. Combining these three prognostic factors in the jackknifed procedure, we could correctly classify 33/37 patients in two groups: grade O-I versus grade II-IV acute GvHD. These results should apply to donor selection and to predict donor/recipient pairs at high risk of GvHD who might benefit of bone marrow T-cell depletion and those at low risk for whom depletion could be avoided.

Adolescent↗
PubMed1988

Reconstructed human epidermis: absence of Langerhans cells and failure to stimulate allogeneic lymphocytes in vitro.

Whole human skin can be reconstructed in vitro, using dermal equivalents made of fibroblasts in a collagen matrix. We recently described a new method of epidermalization of dermal equivalents, based on the insertion of punch biopsies and the migration of epidermal cells (EC) on the reconstructed dermis. In the present study, we show that no MHC class II or T6 positive Langerhans cells (LC) can be detected in this new epidermis. Functional studies with EC of this reconstructed epidermis show that these EC completely fail to induce proliferation of allogeneic lymphocytes in mixed epidermal cell lymphocyte reactions and to raise an allogeneic T cell response. In contrast, fresh EC from the same donors induce a strong proliferative and cytotoxic response of the same effector cells. Moreover, the addition of fresh LC-containing EC autologous to effector lymphocytes does not restore an allogeneic proliferative and cytotoxic response directed against class I different EC of the new epidermis. Such a non-immunogenic whole skin model composed of two compartments, dermis and epidermis, completely devoid of class II-bearing antigen presenting cells, is thus a very promising technique for allogeneic skin grafting in the treatment of burns.

Culture Techniques↗
PubMed1986

A possible predictive test for graft-versus-host disease in bone marrow graft recipients: the mixed-epidermal cell-lymphocyte reaction.

The possible ability of the mixed-epidermal-cell-lymphocyte reaction (MECLR) to detect alloreactivities in HLA-identical MLR negative siblings has been investigated before grafting in 30 donor-recipients pairs and their families. Results indicate that recipients' epidermal cells (EC) can induce proliferative responses of HLA-identical MLR-negative donors' lymphocytes in 55% of the pairs tested. Moreover, further evaluation of 21 patients shows that the positivity of the MECLR before the graft is correlated with later appearance of acute and chronic GVHD, and especially with the severity of cutaneous injury. EC have been shown to be more efficient antigen presenting cells than peripheral blood lymphocytes for in vitro primary proliferative responses, so these reactions could be directed against some minor histocompatibility antigens, thus leading to possible improvement in selecting bone marrow graft donors and to the detection of donor-recipient pairs with a high risk of GVHD.

Adolescent↗
PubMed1986

A new method for studying epidermalization in vitro.

A new method for studying epidermalization in vitro is described. It consists of inserting a punch biopsy that serves as a source of epidermis into dermal equivalent freshly made up, with fibroblasts mixed in a collagen matrix. Fibroblasts cling to collagen fibrils and contract the matrix, leading in 3 days to a resistant dermal equivalent holding the punch biopsy firmly in place. At day 5, a culture medium favouring epidermal growth was used and a fringe of a new epidermis appeared around the punch, the area of which grew linearly with time. This new epidermis showed a pattern of differentiation similar to epidermis in vivo, with cuboidal basal cells, keratohyalin granules, membrane coating granules and the expression of the 65-67 kd keratin subset. The method seems to combine the advantages of the explant technique and of classical keratinocyte cultures, providing the researcher with a large quantity of differentiated epidermis, the pharmacologist with simple and quantitative system in which to study modifications of growth and differentiation of epidermis, and the plastic surgeon with a possible material for skin grafting.

Biopsy↗
PubMed1985

Human epidermal cells are more potent than peripheral blood mononuclear cells for the detection of weak allogeneic or virus-specific primary responses in vitro.

Human epidermal cells (EC) and peripheral blood mononuclear cells (PBMC) have been used as antigen-presenting cells in allogeneic reactions or in self-restricted antiviral responses. Comparison of results from both cell types indicates that: (1) EC were better stimulators of primary proliferative responses in all the antigenic systems tested. (2) In secondary reactions, EC and PBMC functioned similarly for allogeneic responses, while a weak but significant difference could be observed in both (HSV1 or influenza A) virus-specific reactions. (3) By comparing pairs of HLA-identical mixed lymphocyte reaction (MLR)-negative siblings, positive responses were observed in several different families when lymphocytes of potential bone marrow donors were stimulated by EC of the recipient. This suggests that EC might be useful in detecting relatively weak proliferative responses in a number of antigenic systems, but especially in primary reactions against viral or putative minor histocompatibility antigens. (4) Despite this stronger antigen-presenting capacity in proliferative responses, EC induced lower levels of cytotoxic T lymphocyte (CTL) reactions than PBMC, not only in allogeneic responses but also in virus-specific self-restricted reactions.

Adult↗
PubMed1985

Involvement of macrophages in the pathology of toxic epidermal necrolysis.

In toxic epidermal necrolysis (TEN), as in the 'epidermal type' of erythema multiforme, the necrotic epidermis is infiltrated with mononuclear cells. We studied the epidermal infiltrate in seven cases of TEN. About half the cells obtained from pieces of cleaved epidermis dissociated by trypsin were non-epithelial. On cytologic analysis, 80% of these foreign cells exhibited markers of macrophages, 15% were granulocytes and only 5% were lymphocytes (almost exclusively OKT8 T lymphocytes). Semi-thin sections of early prenecrotic lesions showed exocytosis of mononuclear cells within the epidermis with features of satellite cell necrosis and formation of colloid bodies. Almost all these mononuclear cells were macrophages as evidenced by endogenous peroxidase-positive granules. These findings suggest that some kind of macrophage-mediated cytotoxicity may play a role in the necrosis of epidermal cells during TEN.

Adolescent↗