Phenotype and suppressor activity of T-lymphocyte clones extracted from lesions of oral lichen planus

Lymphocytes were extracted from six biopsy specimens of oral lichen planus. T‐lymphocyte lines were expanded in culture with phytohaemagglutinin and interleukin 2, and cloned by limiting dilution. Fifteen T‐cell clones were isolated with a probability of clonality of 96.3%. The majority of clones (n=13) expressed the αβ T‐cell receptor, and of these, 11 were CD8 and two were CD4. Two clones were CD4 and CD8, and expressed the γδ T‐cell receptor. The ability of these clones (effectors) to suppress concanavalin‐A‐stimulated proliferation of autologous lesional T‐cell lines (responders) was assessed. Maximum suppressor activity ranged from 17 to 100%. The majority of clones (n=12), including a CD3 CD4CD8αβ clone, displayed suppressor activity which was proportional to the effector to responder ratio. A CD3CD4CD8αβ clone and a CD3CD4CD8γδ clone displayed substantial helper activity at higher effector to responder ratios. These results demonstrate differential helper and suppressor activity of T‐lymphocyte clones extracted from oral lichen planus lesions. The balance between help and suppression may be a fundamental determinant of immunological activity within the lymphocytic infiltrate of oral lichen planus, and hence may dictate the clinical behaviour of the disease

Clonal expansion of lymphocytes from oral lichen planus lesions

Lymphocytes were extracted from 11 biopsy specimens of oral lichen planus (OLP) by collagenase digestion, and cell lines were expanded with repetitive cycles of stimulation (with phytohaemagglutinin) and rest in media supplemented with interleukin 2. Four OLP lines contained a majority of CD3 + CD4 −CD8 + cells, in six lines the CD4:CD8 ratio was between I and 2, and in one line the CD4:CD8 ratio was 5:1. Limiting dilution of nine lines at 0.3 and 1.0 cells/well resulted in viable wells (putative clones) with plating efficiencies ranging from 0.0 to 18.1 percent and 0.0 to 22.2 percent respectively. The majority of clones were CD3 + CD4–CD8 +αβ+γδ‐, although three clones were CD3 + CD4 + CD8 ‐ αβ+γδ ‐ and one clone was CD3 + CD4 ‐ CDS ‐ and expressed the γδ T cell receptor. T cell clones derived from lymphocytes extracted from OLP lesions may be generated and maintained in culture providing opportunity for their further phenotypic and functional characterisation. This strategy may facilitate the identification of a putative oral lichen planus‐specific antigen and indicate the frequency of lichen planus‐specific T cells within lesions of OLP

Review article: The role of oncogenes, tumour suppressor genes and growth factors in oral squamous cell carcinoma: a case of apoptosis versus proliferation.

Mutation, deactivation and disregulated expression of oncogenes and tumour‐suppressor genes may be involved in the pathogenesis of oral squamous cell carcinoma (SCC). Deactivation of the p53 tumour‐suppressor gene allows cell proliferation and blocks apoptosis of malignant oral keratinocytes. Mutation in the ras oncog‐ene results in persistent mitogenic signalling. Upregul‐ated c‐Myc expression, in the presence of growth factors, provides an additional proliferative signal. Loss of retino‐blastoma tumour‐suppressor gene (Rb) function may contribute to oral keratinocyte hyperproliferation and recent evidence suggests that simultaneous deactivation of both p53 and Rb is required for tumourigenesis. Enhanced Bcl‐2 and reduced Fas expression inhibit tumour cell apoptosis and may convey resistance to cyto‐toxic drugs and T cell‐mediated cytotoxicity, respectively. Exogenous mutagens such as tobacco, alcohol and viral oncogenes may cause altered expression of oncogenes and tumour‐suppressor genes in some cases of oral SCC. The impact of these mechanisms on future therapies for oral SCC is highlighted

Disease mechanisms in oral lichen planus. A possible role for autoimmunity.

Current evidence for the involvement of cell‐mediated immunological mechanisms in the pathogenesis of oral lichen planus is reviewed. Both a spatial and temporal relationship between cytotoxic T Lymphocytes and epithelial damage have been reported. Although keratinocytes appear to be the target for destruction in oral lichen planus, their role in antigen presentation is unclear. We propose that in oral lichen planus patients, diverse exogenous agents such as drugs, trauma and infection, stimulate the expression of a common self molecule by oral mucosal keratinocytes. An autoimmune reaction by cytotoxic T lymphocytes to these activated keratinocytes may result in the tissue destruction which is characteristic of oral lichen planus. Copyrigh

Suppressor cell function in oral lichen planus.

Oral lichen planus (OLP) is a common inflammatory condition of the oral mucous membranes which affects between one and two percent of the general population. In accordance with the protracted clinical course of OLP and its association with known auto-immune diseases, the level of self-tolerance is questionable and possibly diminished in patients with this disorder. Normal suppressor T lymphocyte function is reputedly an essential element in the maintenance of self-tolerance, and deficient cell-mediated suppressor activity is implicated in the pathogenesis of auto-immune diseases. For assessment of in vitro cell-mediated suppressor activity in OLP, peripheral blood mononuclear cells (PBMC) from ten patients with OLP and from 11 control subjects were activated with the plant mitogen concanavalin A (Con A), followed by co-culture with autologous responder cells. The ability of irradiated Con A-activated cells to suppress the proliferation of Con A-stimulated responder cells was determined. Con A-induced suppressor activity of PBMC in the OLP patients was significantly less than that in control subjects (p = 0.001). Results of the present investigation complement previous in vitro findings which provided indirect evidence of deficient cell-mediated suppressor activity in OLP, particularly a decreased proportion of circulating CD4+CD45RA+ lymphocytes and reduced Con A-stimulated PBMC proliferation. The depressed Con A-induced suppressor activity of PBMC in the OLP patients provides direct evidence of deficient in vitro cell-mediated suppressor function in OLP, and suggests that defective cell-mediated suppressor circuits and reduced self-tolerance may be involved in the pathogenesis of this disorder

P-gingivalis-specific T-cell lines produce Th1 and Th2 cytokines

Cytokines produced by T-cells in periodontal lesions may determine the nature of the adaptive immune response. Since different antigen-7 presenting cells (APC) may direct the Th1/Th2 response, P. gingivalis-specific T-cell lines were established by different APC subpopulations, and their cytokine profiles were determined. Peripheral blood mononuclear cells induced similar percentages of IL-4+ and IFN-gamma+ T-cells and lower percentages of IL-10+ T-cells, Epstein-Barr virus-trans formed B-cells (LCL) induced higher percentages of IL-4+ cells than IFN-gamma+ cells, with lower percentages of IL-10+ cells. Peripheral blood mononuclear cells induced a higher percent of IFN-gamma+ CD8 cells than LCL (p = 0.004). Purified B-cells, monocytes, and dendritic cells induced similar percentages of IL-4+ and IFN-gamma+ cells, although again, the percentage of IL-10+ cells was lower. The results of the present study have demonstrated that, as measured by FACS analysis of intracytoplasmic cytokines, P. gingivalis-specific T-cells produce both Th1 and Th2 cytokines, regardless of the APC population

TCR Vβ gene expression in lesional T lymphocyte cell lines in oral lichen planus

To study V beta gene expression in oral lichen planus (OLP) lesional T lymphocytes cell lines.Lesional T lymphocytes were isolated from eight OLP patients and cell lines established. The total RNA was extracted from these lymphocyte cell lines and reverse transcribed. cDNA was amplified by the polymerase chain reaction (PCR) using a panel of 26 V beta-specific oligonucleotide primers followed by qualitative analysis of the electrophoresed reaction products.V beta 1, 2, 3, 5.1, 6.1-3, 7, 8, 9, 22, 23, and 24 were represented consistently in all of the OLP samples, V beta 11, 12, and 17 were consistently negative, while the other V beta families (V beta 4, 5.2-3, 10, 13.1, 13.2, 14, 15, 16, 18, 19, 20, and 21) were variable. V beta 22 and 23 were the most strongly expressed in all patients.A limited T cell receptor (TCR) gene usage indicates a degree of oligoclonality within these lesional T lymphocyte cell lines from OLP. This implies that OLP may be an antigen-specific disease or linked to a limited number of superantigens

Cell-surface proteoglycan expression by lymphocytes from peripheral blood and Gingiva in health and periodontal disease

Cell-surface proteoglycans are involved in lymphocyte migration and activation. This study investigated the expression of syndecan-1, syndecan-4, and glypican in peripheral blood lymphocytes and by lymphocytes in variously inflamed periodontal tissues. Gingival specimens from healthy, gingivitis, or chronic periodontitis sites were stained by means of antibodies against B- and T-lymphocytes and also syndecan-1, syndecan-4, and glypican. Syndecan-1 expression by peripheral blood mononuclear cells (PBMC) from healthy, gingivitis, and chronic periodontitis subjects was assessed by flow cytometry. Syndecan-1 was expressed by B-cells/plasma cells but not T-cells in both gingivitis and chronic periodontitis lesions, Both B-cells/plasma cells and T-cells in gingivitis and chronic periodontitis expressed syndecan-4. Glypican was expressed only by macrophages. Stimulation of PBMC with mitogens and growth factors modulated syndecan-1 expression in both the T- and B-cells. Thus, cell-surface proteoglycan expression by lymphocytes in periodontal inflammation is cell-type-specific and may be modulated by inflammation