Cellular immunosuppression in oral lichen planus

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Abstract
Functions of peripheral blood lymphocytes and neutrophils from 30 oral lichen planus (OLP) patients were examined using healthy persons as controls. Two‐color flow cytometry of lymphocytes revealed no proportional difference in CD3 or CD4 cells between OLP and controls. CD8CD 11b (suppressor T) and CDSHLA‐DR+ cell populations increased significantly in OLP when compared with controls, and, CD4/CD8 cell ratio decreased in OLP. Mitogenic response of patients' CD8 and CD4Leu8‐ cells was similar to that in controls. However, weaker blastogenesis of CD4Leu8+ cells, the most excellent responders in T cell subsets, was observed in OLP. Serum IFNβ level in OLP (8.4±4.8 IU/ml) was significantly lower than in controls (13.7±5.0 IU/ml) whereas no difference between the two groups could be found in IFNα or γ. As for in vitro cytokine production by IL‐2‐stimulated lymphocytes, there was no difference in GM‐CSF generation between the two groups, but, IFNγ and IL1β production of patients' lymphocytes was less than that in healthy donors (57.6 ± 50.7 VS 78.7 ± 39.6 u/ml. 152.3 ± 93.5 VS 258.7 ± 65.4 pg/ml, respectively). Moreover, superoxide generation of patients' neutrophils by PMA stimulation was significantly insufficient as compared with controls' (84.9±30.9 VS 110.8±24.1 pmol/min/104 cells). Nevertheless, natural killer cell activities of both groups distributed in the same range. These results suggest that OLP patients' lymphocyte and neutrophil functions are impaired, and that cellular immunosuppression is a pathologic characteristic of OLP.