concanavalin-a and Lichen-Planus

It is well known that cell surface glycoconjugates play an important role in cell proliferation, adhesion and differentiation. The aim of this investigation was to define the changes of the glycoconjugate saccharidic moieties in the epidermis and derma of patients affected by several skin pathologies such as seborrheic keratosis, lichen planus, granuloma annulare and palmoplantaris keratoderma. Bioptical specimens from skin lesions as well as from normal skin were fixed in Carnoy's fluid and routinely processed. The sections were treated with HRP-lectins (PNA, DBA, SBA, WGA, ConA, LTA and UEAI). Cytochemical controls were performed for specificity of lectin-sugar reaction. Some sections were pre-treated with neuraminidase prior to staining with HRP lectins. In comparison with normal human skin, epidermal lectin binding pattern in the considered diseases showed considerable qualitative and quantitative variations. In general, in all the considered pathologies, a lack and/or a decrease in lectin binding at the epidermal layers was observed; among the various diseases, differences in cellular localisation of the sugar residues were also noted. In such respect, an exception was represented by seborrheic keratosis, where the cells of the basal layer showed PNA reactivity, which was absent in the basal layer of the normal skin. Although seborrheic keratosis and lichen planus have been studied by others authors, our findings are not in total accordance concerning lectin binding; this is probably due to the different fixatives employed. Our findings seem to reveal significant changes in keratinocyte glycoconjugate oligosaccharides in the previously mentioned diseases, providing clues to their pathogenesis.

Topics: Concanavalin A; Glycoconjugates; Granuloma Annulare; Humans; Keratoderma, Palmoplantar; Keratosis, Seborrheic; Lectins; Lichen Planus; Oligosaccharides; Peanut Agglutinin; Plant Lectins; Wheat Germ Agglutinins

To assess cellular immunity in oral lichen planus (OLP), peripheral blood mononuclear cells (PBMC) were obtained from 19 OLP patients and 30 control subjects. The proportions of circulating CD45RA+ and CD29+ lymphocyte subsets were determined. The proliferative activity of PBMC to the non-specific plant mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) was examined together with the spontaneous proliferative response and the response in the autologous mixed lymphocyte reaction (AMLR). In the OLP group, the proportion of CD4+ CD45RA+ T lymphocytes was significantly less than control subjects and the proportion of CD4+ CD29+ T lymphocytes was increased significantly. The proliferative response to PHA was similar in OLP and controls subjects. Con A-stimulated PBMC proliferation was decreased significantly in the OLP group. Spontaneous PBMC proliferation in patients with non-reticular lesions was significantly less than control subjects. Despite a mildly depressed response in the AMLR in OLP patients, this result was not statistically significant. Results of the phenotypic analysis of peripheral blood lymphocytes indicate a decreased proportion of naive T cells and an increased proportion of primed memory T cells, although the antigen specificity of these memory cells remains to be determined. Results of the functional assays would seem to reflect this phenotypic shift, and as T cells responding to Con A stimulation and in the AMLR possess suppressor-inducer activity, these results may also suggest an association between OLP and defective innate T cell-mediated suppressor circuits.

Topics: Adult; Aged; CD4-Positive T-Lymphocytes; Cell Division; Concanavalin A; Female; Fluorometry; Humans; Leukocyte Count; Lichen Planus; Lymphocyte Activation; Male; Middle Aged; Mouth Diseases; Phenotype; Phytohemagglutinins; Sex Factors; T-Lymphocyte Subsets; T-Lymphocytes, Cytotoxic

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.

Topics: Adult; Aged; Concanavalin A; Female; Humans; Immunity, Cellular; Lichen Planus; Lymphocyte Activation; Male; Middle Aged; Mouth Diseases; T-Lymphocytes, Regulatory