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M Alaibac

Publications and source records attributed to M Alaibac.

29 records · Page 2Linked to original sources
PubMed1993

Gamma delta T lymphocytes in oriental cutaneous leishmaniasis: occurrence and variable delta gene expression.

It has been suggested that T lymphocytes expressing gamma delta T-cell receptors could play an important role in defence against some intracellular infectious pathogens. The present study was undertaken to characterize the occurrence and variable delta gene expression of T lymphocytes expressing the gamma delta T-cell receptor in oriental cutaneous leishmaniasis. Eleven cases of oriental cutaneous leishmaniasis were investigated by immunohistological analysis using an alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique. In three cases, we observed an increased percentage of gamma delta T cells (about 20% of CD3+ cells). In these cases gamma delta T cells generally expressed the V delta 2 segment, and only rarely the V delta 1 gene product. V delta 2+ cells were predominantly localized in the dermis, and were virtually absent in the epidermal compartment. The rare gamma delta T cells observed in the epidermis were almost exclusively V delta 1+. This study demonstrates that an increase of gamma delta T cells may be found in oriental cutaneous leishmaniasis, although it is not a constant feature of the disease. The finding of a preferential expansion of the V delta 2 subset suggests that this subpopulation of gamma delta T cells might be selectively involved in the recognition of Leishmania antigens. The distinct compartmentalization of gamma delta T-cell subpopulations indicates that these subsets may recognize distinct sets of antigens.

Antigens, Protozoan↗
PubMed1993

Molecular analysis of the gamma delta T-cell receptor repertoire in normal human skin and in Oriental cutaneous leishmaniasis.

The extent of diversity of the gamma delta T-cell receptor (TCR) in normal human skin and Oriental Cutaneous Leishmaniasis (OCL) was examined by molecular analysis of the variable (V) delta gene segment, junctional (J) delta gene segment and junctional regions. To examine the expression of TCR delta genes, segments of gamma delta T lymphocytes, DNA isolated from normal human skin and from OCL were subjected to enzymatic gene amplification by the polymerase chain reaction (PCR) method using TCR V delta- and J delta-specific oligonucleotides as primers. PCR amplification using these primers indicated that the V delta 2 gene segment was predominantly used by gamma delta T lymphocytes in both normal human skin and OCL. To determine the extent of junctional diversity in the delta gene of gamma delta T cells in normal human skin and OCL, we sequenced the nucleic acid sequences corresponding to the V delta 2/J delta 1 junctional regions. Sequence analysis of junctional regions demonstrated broad junctional diversity in normal skin but only limited diversity in OCL. Our findings support the hypothesis that skin gamma delta T lymphocytes may derive from a fetal subset of gamma delta T lymphocytes that leaves the thymus early and colonizes the periphery. The limited junctional diversity demonstrated in OCL lesions indicates that gamma delta T cells can undergo oligoclonal expansion following recognition of a specific ligand and supports the idea that junctional regions are important in the recognition of antigenic determinant.

Amino Acid Sequence↗
PubMed1992

Purification of functional active epidermal Langerhans cells: a simple and efficient new technique.

Our knowledge of the functional activity of the epidermal Langerhans cell has been severely hampered by the lack of an easy method of purification of these cells that is both efficient and reproducible. In the present study we have used immunomagnetic beads directly conjugated to an IgM class mouse anti-human human leukocyte antigen DR monoclonal antibody to positively select human Langerhans cells from an epidermal cell suspension. Cells were then treated with a high-affinity polyclonal anti-mouse immunoglobulin that detached the beads by competing with the antigen for the antigen-binding site on the monoclonal antibody. This procedure allowed removal of the immunomagnetic beads, leaving Langerhans cells free from bound antibody. Recovery of Langerhans cells ranged from 40 to 80% of the starting number of Langerhans cells. The resulting cells were up to 99% CD1a positive and showed potent functional activity in the allogeneic mixed epidermal cell - lymphocyte reaction. Keratinocytes were shown to exert a profound inhibitory effect on Langerhans cell function that could not be prevented by indomethacin. This method is technically simple and allows good recovery of a highly purified population of Langerhans cells that are functionally active.

Cell Separation↗
PubMed1992

T lymphocytes bearing the gamma delta T-cell receptor: a study in normal human skin and pathological skin conditions.

The aims of this study were to investigate the presence of gamma delta T cells in normal human skin, and the possible role of these cells in cutaneous reactions. Twenty-eight samples of normal skin from various sites, and 52 biopsies from inflammatory and neoplastic skin conditions were investigated by immunohistochemical techniques. In normal human skin gamma delta T cells were infrequently seen in the epidermis and dermis. In the inflammatory and neoplastic dermatoses, gamma delta T cells were occasionally present, accounting for 0-5% of CD3+ cells in most of the biopsies examined. In one case of pityriasis lichenoides chronica and one case of lichen planus gamma delta T cells were found to be increased, accounting for 15% of the CD3+ cells in each case. Dermal gamma delta T cells were markedly increased in three of six cases of Langerhans cell histiocytosis, with up to 30% of dermal CD3+ cells showing positive staining to an anti-T-cell receptor gamma delta monoclonal antibody. In two of these cases gamma delta T cells were seen in both the dermis and the epidermis. In two further cases dermal gamma delta T cells were not a prominent feature, but small clusters of epidermal gamma delta T cells were observed. T cells bearing the gamma delta T-cell receptor are thus not a major feature of normal human epidermis, unlike the murine system, where the great majority of epidermal lymphocytes express the gamma delta T-cell receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermis↗
PubMed1990

["Specific" skin lesions in chronic lymphatic leukemia].

Infiltrated skin lesions, histologically characterized by a perivascular and periadnexal lympho-histiocytic infiltrate in the upper and deep dermis, are quite frequently observed in patients with B-cell chronic lymphocytic leukemia (C-CLL). The correct identification of the actual nature of these lesions, defined as specific on clinical and histologic grounds, is essential for a proper staging of the disease and, consequently, for the prognostic evaluation. In 6 patients with B-CLL, we performed an immunohistochemical study of specific skin lesions, with the aim of exactly defining the actual nature of infiltrating cells. Only in 2 of 6 cases immunophenotyping evidenced the neoplastic B-cell nature of skin infiltrating lymphoid cells; this finding was clearly correlated with the clinical evolution of the disease, rapidly fatal in both cases. The results of the present study indicate that the immunohistochemical analysis of skin lesions allows the proper staging of the disease, thus giving an important prognostic indication.

Aged↗
PubMedDate not supplied

Immunoglobulin heavy chain gene rearrangement in B-cell non-Hodgkin's lymphomas detected by the polymerase chain reaction.

AIMS AND BACKGROUND: Immunoglobulin heavy chain gene rearrangement serves as a marker of clonality and cell lineage in B-cell lymphoproliferative disorders. In this study we used the polymerase chain reaction (PCR) to detect clonal rearrangements of the immunoglobulin heavy chain gene in a group of patients with B-cell lymphomas. METHODS: DNA was extracted from frozen tissue of 40 B-cell non-Hodgkin's lymphomas and subjected to PCR amplification using primers that recognize conserved sequences of the variable and joining regions of the immunoglobulin heavy chain gene. RESULTS: Monoclonal rearrangements were detected in 23 of 40 malignant B-cell lymphomas. No clonal rearrangements were detected in the 10 control cases. CONCLUSIONS: We conclude that this PCR-based technique may provide a simplified and rapid approach for the detection of clonal immunoglobulin heavy chain gene rearrangements in B-cell lymphomas without recourse to Southern blotting, which can be reserved for cases in which PCR is negative.

Base Sequence↗
PubMedDate not supplied

IL-16 serum level in children with atopic dermatitis.

IL-16 is a natural ligand of CD4 molecules and induces chemotaxis in CD4-expressing cells. It amplifies the inflammatory reaction by stimulating cytokine production in monocytes and activating T-cells. There is evidence that IL-16 plays a role in the pathogenesis of atopic dermatitis, and increased serum levels of IL-16 have been detected in allergic diseases. However, few data are available on IL-16 serum levels in atopic dermatitis. The aim of our study is to measure IL-16 serum levels in childhood atopic dermatitis before and after treatment and to evaluate a possible correlation between IL-16 serum levels and disease severity. IL-16 serum levels were measured by an ELISA approach in 34 children (19 males and 15 females; mean age 6.8 years) with moderate to severe atopic dermatitis, at their first visit and after 3 months of treatment, and in 10 non-atopic healthy controls of the same age group. The severity of atopic dermatitis was measured by SCORAD index. IL-16 serum levels were significantly higher in patients affected by atopic dermatitis than in controls before and after treatment with tacrolimus ointment. No clear correlation was found between IL-16 serum levels and atopic dermatitis severity. IL-16 serum levels are increased in atopic dermatitis but do not seem to correlate with disease severity.

Adolescent↗
PubMedDate not supplied

Polymerase chain reaction analysis of T-cell receptor gamma gene rearrangements in cutaneous B-cell lymphomas.

PCR analyses of T-cell receptor (TCR) gamma gene rearrangements in B-lymphoid neoplasms have shown lineage infidelity and double rearrangements involving both immunoglobulin heavy chain (igH) and TCRgamma genes. In order to investigate if this event is also a feature of cutaneous B-cell malignancies, we tested for clonal TCRgamma rearrangements a panel of immunophenotypically and genotypically well characterized cutaneous B cell lymphomas (CBCL). Fifteen samples of frozen CBCL biopsies were selected for the study. Diagnoses were established by routine histology and immunohistochemistry. Each of these cases displayed clonal igH gene rearrangement. Polymerase chain reaction (PCR) analysis of the TCRgamma rearrangements followed by high-resolution polyacrylamide gel electrophoresis was utilized for detection of clonal TCRgamma rearrangements. In our investigation, none of the cases of CBCL investigated by PCR showed the presence of clonal TCRgamma gene rearrangements. These data indicate that double rearrangements involving both igH and TCRgamma genes are not a feature of CBCL and confirm the B cell lineage specificity of this group of cutaneous lymphoid neoplasms.

DNA Primers↗
PubMedDate not supplied

Role of cellular immunity in the pathogenesis of autoimmune skin diseases.

The pathomechanism of most autoimmune skin diseases is still elusive; however, recent clinical and basic research is leading novel insights into the cellular and molecular biological underlying pathways. Several types of infectious skin diseases are infiltrated by significant number of gamma/delta T cells and similar observations have been made in selected immune-mediated skin conditions. In particular, a role for gamma/delta T cells has been suggested in discoid lupus erythematosus, contact dermatitis, herpetiformis dermatitis, necrotizing cutaneous vasculitis, and cutaneous lesions of systemic sclerosis. The pathogenesis of these diseases is different and this may suggest multiple potential functions of this subset of T cells in the immune system of the skin. Furthermore, most T cells infiltrating tissue and organs undergoing fibrosis have the potential to produce high levels of interleukin 4. This is particularly true for the CD8+ or CD4+ CD8+ double positive T-cell subsets. Furthermore, leukocyte recruitment is a key event in immunity and a better understanding of the signals involved in autoimmune diseases constitutes a valuable basis for the development of new strategies, which control leukocyte migration and function under pathological conditions.

Apoptosis↗
PubMedDate not supplied

Analysis of clonal antigen receptor gene rearrangements in T-cells involved with Kaposi's sarcoma.

Kaposi's sarcoma (KS) is a multifocal neoplasm of unknown origin. All forms of KS are composed of spindle-shaped cells with elongated nuclei and sheets of endothelial-like cells. The proliferation of spindle cells is accompanied by the presence of an inflammatory infiltrate composed predominantly of T-cells. It has been suggested that this infiltrate might consist of a virally stimulated clonal population of T-lymphocytes which can produce growth factors initiating and substaining the proliferation of spindle-shaped cells. In this study we analyzed for clonal T-cell receptor gama gene rearrangements the T-cell populations present in the cutaneous infiltrate of seven cases of classical Kaposi's sarcoma using a polymerase chain reaction-based approach. Our data demonstrate the lack of a significant clonal population of T-cells in the cutaneous infiltrates of KS. This finding is indicative of a reactive polyclonal response of T-cells to the spindle-shaped cells and supports the contention that spindle-shaped cells are pathogenetically the central cell type in the disease. Our data also indicate that the anti-KS T-cell response, being polyclonal in nature, does not result from clonal expansion of T-cells targeting tumor-associated antigenic peptides.

Gene Rearrangement, gamma-Chain T-Cell Antigen Rec↗