Expression of CDw29 and CD45R antigens on epithelial cells in oral lichen planus

Update on oral lichen planus: etiopathogenesis and management

Lichen planus (LP) is a relatively common disorder of the stratified squamous epithelia, which is, in many ways, an enigma. This paper is the consensus outcome of a workshop held in Switzerland in 1995, involving a selection of clinicians and scientists with an interest in the condition and its management. The oral (OLP) eruptions usually have a distinct clinical morphology and characteristic distribution, but OLP may also present a confusing array of patterns and forms, and other disorders may clinically simulate OLP. Lesions may affect other mucosae and/or skin. Lichen planus is probably of multifactorial origin, sometimes induced by drugs or dental materials, often idiopathic, and with an immunopathogenesis involving T-cells in particular. The etiopathogenesis appears to be complex, with interactions between and among genetic, environmental, and lifestyle factors, but much has now been clarified about the mechanisms involved, and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory, and there is as yet no definitive treatment, but there have been advances in the control of the condition. There is no curative treatment available; immunomodulation, however, can control the condition. Based on the observed increased risk of malignant development, OLP patients should be offered regular follow-up examination from two to four times annually and asked to report any changes in their lesions and/or symptoms. Follow-up may be particularly important in patients with atrophic/ulcerative/erosive affections of the tongue, the gingiva, or the buccal mucosa. Much more research is required into the genetic and environmental aspects of lichen planus, into the premalignant potential, and into the possible associations with chronic liver, and other disorders. More clinical studies are required into the possible efficacy of immunomodulatory drugs such as pentoxifylline and thalidomide.

Intra-epithelial subpopulations of T lymphocytes and Langerhans cells in oral lichen planus

This study has addressed the question of whether there is selective recruitment and distribution of intra-epithelial leucocytes in lesions of oral lichen planus (OLP). T-lymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cytometry and double immunofluorescence, and the relationship between keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined. The circulating 'memory' subset (CD45RO+) of T-helper cells (CD4+) was increased from 49.1% in controls to 65.7% in patients (P=0.005), while the 'naive' subset (CD45RA+), which was absent from control epithelium, comprised 24% of helper cells in OLP (P=0.016). Fewer LC expressed CD45RO in OLP than in controls (P=0.037) and all T-cell and LC counts were significantly raised in ICAM-1-expressing areas of epithelium. These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is selective recruitment in OLP. In addition, keratinocyte ICAM-1 expression does appear to be associated with accumulation of infiltrating T lymphocytes and LC.

Cellular immune correlates of clinical severity in oral lichen planus: preliminary association with mood states

OBJECTIVES

We investigated cellular immune and psycho-immune dysfunctions in patients with erosive and non-erosive oral lichen planus (OLP) lesions.

METHODS

Patients with erosive or non-erosive OLP were screened at the UCLA Dental Clinic. The profile of mood states (POMS) was administered. T lymphocyte subpopulations were monitored by dual fluorescence. T lymphocytes were stimulated with phytohemagglutinin (PHA) for assessment of markers of activation by flow cytometry and of interleukin (IL)-2 production by ELISA. Plasma cortisol and neopterin levels were assessed by radioimmunoassay.

RESULTS

Circulating T cells that express the cluster of differentiation no. 4 (CD4+) but devoid of the CD45RA marker, and POMS score were significantly associated (r = 0.83, P < 0.05) in the patients we studied. We found a significantly higher (P < 0.05) per cent and absolute lymphocyte numbers of circulating CD4+CD45RA- cells in the OLP patients with erosive lesions, compared to OLP patients with non-erosive lesions. The ratio of CD4+ CD45RA+ over CD4+CD45RA- cells was significantly (P < 0.05) biased toward the CD4+CD45RA- subpopulation in OLP patients with erosive lesions (ratio = 0.19 +/- 0.09) compared to patients with non-erosive OLP lesions (ratio = 0.47 +/- 0.15). The expression of CD54, but not that of CD69, was significantly blunted (P < 0.05) in OLP patients following CD3+ cell stimulation. IL-2 production and plasma neopterin were normal in these patients. There was no correlation between plasma cortisol and T cell populations.

CONCLUSIONS

We find fine differences in psycho-immune interactions between patients afflicted with non-erosive OLP lesions compared to those with erosive OLP lesions.

Immunologic aspects of dermal and oral lichen planus: a review

There have been many investigations, both experimental and epidemiologic, of the forms of LP affecting the skin and oral mucosae. These studies have provided a varied range of hypotheses to explain not only the factors determining susceptibility to and onset of this disease, but also the immunologic mechanisms leading to the pathosis with which LP is associated. Much progress has been made, especially through in vitro studies, regarding detailed aspects of the immunology of LP. However, data is often conflicting or incomplete. In this review we attempt to bring together the currently available data regarding the immunologic basis of LP.

Expression of lymphocyte function-associated antigen 3 in oral lichen planus

OBJECTIVE

The expression pattern of lymphocyte function-associated antigen 3 (LFA-3) in the buccal mucosa of oral lichen planus (OLP) patients was compared to that of healthy controls to investigate the possible role of LFA-3 in cell interactions within OLP lesions.

MATERIALS AND METHODS

Samples of buccal mucosa from 17 clinically healthy individuals and 17 OLP lesions were analysed. Expression of LFA-3, CD2, CD3 and CD14 was visualized by an immunoperoxidase technique and assessed microscopically.

RESULTS

In healthy buccal mucosa LFA-3 was expressed on keratinocytes, Langerhans cells within the epithelium and on endothelial cells in the lamina propria. In OLP patients a similar pattern of LFA-3 staining was observed. In addition, cytoplasmic LFA-3 without accompanying surface staining, was seen on a subpopulation of macrophage-like cells. Substantial amounts of LFA-3 also appeared to be associated with non-cellular components of the extracellular matrix within the inflammatory infiltrate.

CONCLUSIONS

We have obtained evidence for a previously undescribed localization of LFA-3 within macrophages, and have observed that expression of LFA-3 is apparently elevated within OLP lesions. LFA-3 may play an important role in the pathogenesis of OLP.

Alteration in peripheral blood mononuclear cell function and serum cytokines in oral lichen planus

Different activation parameters of peripheral blood mononuclear cells (PBMC) from 31 patients with oral lichen planus (OLP) were examined and compared with 23 healthy donors. Impaired spontaneous (450 +/- 241 vs 1290 +/- 480 cpm) and mitogen-induced (39580 +/- 14470 vs 67000 +/- 11810 cpm) lymphocyte blastogenesis was observed in OLP patients. Furthermore, reduced cytokine production was found after phytohemagglutinin A (PHA) stimulation for all cytokines studied-tumour necrosis factor alpha (TNF alpha, 432.2 +/- 73.4 vs 979.8 +/- 46.3 units/ml), interleukin 2 (IL-2, 156.2 +/- 14.9 vs 572.6 +/- 12.9 pg/ml), interferon gamma (IFN gamma, 48.5 +/- 11.9 vs 82.6 +/- 12.4 pg/ml) and interleukin 6 (IL-6, 253.6 +/- 57.7 vs 1,419.0 +/- 279.6 units/ml)-except for interleukin 1 beta (IL-1 beta) and lymphotoxin (LT). In contrast, unstimulated culture supernatants showed increased TNF alpha (38.2 +/- 13.1 vs 8.0 +/- 0.2 units/ml), LT (10.2 +/- 2.2 units/ml vs < 0.4) and IL-6 (18.5 +/- 5.6 units/ml vs < 0.5) activity. Similarly, elevated concentrations of TNF alpha (19.6 +/- 6.3 units/ml) and IL-6 (22.9 +/- 4.7 units/ml) were detected in the sera of OLP patients. Combination of PHA and phorbol myristate acetate (PMA) could restore OLP proliferative T cell response and cytokine production to the level of healthy donors, whereas exogenous recombinant human IL-2 (rhuIL-2) plus PMA did not seem to be an effective stimulant for OLP T cells. These results indicate an alteration in the immune condition of OLP patients and an impairment in T lymphocyte function.

Langerhans cells: structure, function and role in oral pathological conditions

Langerhans cells (LCs) are dendritic bone marrow derived cells situated suprabasally in most stratified squamous epithelia, such as the epidermis and the epithelium of oral mucosa, including the gingiva. Langerhans cells are thought to act as antigen-presenting cells (APC) during induction of immune responses. The exact role of Langerhans cells in the oral mucosa is not fully understood although several investigations suggest that these cells are involved in reactions to antigen challenge under both normal and pathological situations. In this paper the structure, phenotypic markers and derivation of Langerhans cells are reviewed. In view of recent findings, the immunological characteristics and the implications of Langerhans cells in pathologic oral reactions are discussed.

Oral lichen planus. A review

Lichen planus is a mucocutaneous disease of unknown etiology which, according to current knowledge, may represent a cell-mediated immunological response to induced antigenic changes in the skin and mucosa. Oral lichen planus (OLP) is a disease of adulthood and as one of the most prevalent diseases affecting the oral mucosa it has been the subject of intensive research during recent years. Ultrastructural and immunohistochemical studies particularly dealing with the subepithelial inflammatory cell infiltrate and its relations to epithelial pathology, the basal cell region and the intraepithelial antigen presenting Langerhans' cells, have contributed vastly to our knowledge of the pathogenesis of OLP. However, the treatment of OLP still remains largely symptomatic because many as yet unknown factors, active in the disease process, still remain to be elucidated.

Immunopathogenesis of oral lichen planus

Oral lichen planus (LP) is a common mucosal disorder in which cell mediated immunity is thought to play a major role. In this paper, a unifying hypothesis which attempts to integrate cellular and molecular signals in the local immune response in oral LP is presented. In this model, modified keratinocyte surface antigens are the target for the cytotoxic cell response which characterizes oral LP, whereas mast cells and antigen presenting Langerhans cells are key cellular elements in the evolving lesion. It has been established that mast cell degranulation induces adhesion molecule expression on endothelium which facilitates lymphocyte homing to the tissues. These adhesive interactions between lymphocytes and keratinocytes are postulated to be important determinants in the effector phase of the lesion. Cytokines produced by both lymphocytes and keratinocytes which influence the local immune response could promote chronicity. Accordingly, modulation of immunologic events is a potential therapeutic approach for oral LP.

Modulation of Langerhans cell surface antigen expression by recombinant cytokines

This study examined the influence of cytokines on surface antigen expression by gingival Langerhans cells (LC) in organ culture, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) upregulated the expression of CD1a, HLA-DR and HLA-DP antigens on LC. TNF-alpha, interleukin-4 (IL-4), and transforming growth factor beta (TGF-beta) suppressed CD29 expression, while other cytokines, including interleukin-3 and granulocyte-macrophage colony stimulating factor, were without effect. No cytokines induced CD3, CD4, CD23, CD25 or CD45 RA antigen expression in organ culture. Since TNF-alpha and IL-6 can be secreted by keratinocytes, these molecules, together with interleukin-1, are likely to play a role in the local control of LC number and function within the epithelial milleu. Thus, alterations in cytokine secretion by keratinocytes may at least in part be responsible for variations in LC number and antigen expression which occur in oral mucosal disorders.

Immunohistologic analysis of epithelial cell populations in oral lichen planus

Previous studies have demonstrated heterogeneity within lesional lymphocytes in drug-related oral lichen planus (D-LP) and idiopathic lichen planus (I-LP). This study examined the phenotype of Langerhans cells (LC) and keratinocytes in non-erosive D-LP and I-LP. In I-LP, keratinocytes expressed HLA-DR antigens whilst LC co-expressed CDIa, MHC Class II and CD4 antigens. The high levels of expression of MHC Class II antigens by LC were maintained during short term organ culture. In I-LP, the epithelium contained occasional CD25+ dendritic cells (putative activated LC). These cell phenotypes are suggestive of cell activation and likely result from local production of gamma interferon. In D-LP, expression of MHC Class II antigens on LC was reduced and no CD25+ cells were detected. The epithelium contained an increased number of CD45RA+ dendritic cells. While no differences between the production of interleukin-1 and interleukin-1 inhibitors by tissue samples could be detected, it is likely that the variations in epithelial cell phenotypes in I-LP and D-LP reflect altered cytokine production.