Letters to the Editor Dermatologica 175: 47-52 (1987) Preserved Short-Living Suppressor T Lymphocyte Function in Lichen planus Sir, Suppressor T lymphocytes have an important func tion in the regulation of the immune response. In peripheral blood of patients with active lichen planus (LP) using monoclonal antibodies, elevated OKT4/OKT8 T cell ratios and decreased percentages of OKT8-positive T lymphocytes have been detected recently [1, 2). Furthermore, previous reports have in dicated that LP can occur in association with derma toses associated with immunological disturbances, e.g., pemphigus vulgaris and foliaceus, bullous pem phigoid, alopecia areata and vitiligo [3,4]. In addition, LP has been observed in patients with ulcerative coli tis, systemic lupus erythematosus, thymoma, myasthe nia gravis and hypogammaglobulinemia [4, 5]. Conse quently, we investigated the suppressor function of short-living circulating mononuclear cells in our pa tients with LP. Various methods are employed to measure suppres sor activity of peripheral blood mononuclear cells (PBMC). Bresnihan and Jasin [6] demonstrated that human PBMC stimulated by suboptimal concentra tions of concanavalin A (ConA) after 24 h of incu bation at 37 °C exhibited significantly more -'H- thymidine intake than cells stimulated at 0 h. This difference was interpreted as an indication of a deple tion of short-living suppressor cells during the incuba tion period. Based on these observations the afore mentioned authors described a method to detect sup pressor function of human PBMC. The phenomenon of ConA-induced suppression and the enhanced stimulation of PBMC which follows the delayed addi tion of mitogen were both confirmed by Feighery et al. [7]. This method was utilized in our study to investigate the suppressor activity of PBMC in patients with LP. 11 patients (5 females, 6 males) with clinically and histologically confirmed LP of skin and/or oral muco sa were included in the study. The mean age was 41 years with a range of 26-55 years. Mean duration of disease was 6 weeks with a range of 3 weeks to 5 months. No patient had low peripheral blood total lymphocyte counts or had received topical or systemic immunosuppressive treatment for at least 3 months. Eleven healthy sex- and age-matched volunteers served as controls. In the control group the mean ± SEM of Si was found to be 3.03 ± 2.19 while in patients with LP it proved to be 2.82 ± 1.92. The difference between the two groups proved not to be statistically significant (p > 0.05). Suppressor cells have been found to have an impor tant role in immunological tolerance, antigenic compe tition, genetic control of the immune responses, allo type suppression and the regulation of the response to different antigens. Disorders involving suppressor cell activity p'.ay a role in the pathogenesis of some hu moral immunodeficiencies, anergy associated with fungal infection, several autoimmune diseases and in the immunological enhancement of tumor growth. Examinations of different lymphocyte subpopula tions in cutaneous inflammatory infiltrate of active LP have revealed the existence of T lymphocytes of both OKT4/Leu-3a- and OKT8/Leu-2a-positive pheno type. Recent studies clearly documented that a signifi cantly higher OKT4/OKT8 T lymphocyte ratio and a reduced percentage of the OKT8-positive T cell subset in peripheral blood are characteristic of active LP [ 1, 2]. To date, there is little data available concerning var ious functional properties of different lymphocyte subsets in LP [8]. In a recent study we observed a decreased natural killer cell (NK) activity (NKs display OKT3/Leu-9 and a fraction of them OKT8/Leu-2a antigens as well) in this disease [9], In the present study normal suppressor function of peripheral blood T lymphocytes was found in LP using a spontaneous suppressor cell assay described by Bresnihan and Jasin [6]. This finding suggests that immunological abnor malities in LP cannot be related to a primary sup pressor T cell defect. However, impairments of other aspects of the immune regulation in this disease, such as antigen-specific T cell regulation, cannot be ruled out and need further investigations. M. Simon, Jr, MD J. Hunyadi, MD O.P. Hornstein, MD Department of Dermatology University of Erlangen-Niirnberg Hartrr.annstrasse 14 D-8520 Erlangen (FRO) Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/6/2018 10:07:37 PM