Background: Lichen planus is a common chronically relapsing autoimmune skin condition with poorly understood etiology. Apart from cellular immunity, presence of various antibodies has been hypothesized. Various studies have found the presence of serum anti-nuclear antibody, anti-mitochondrial antibody, anti-desmoglein 1 and 3 antibodies, anti-keratinocyte antibody and anti-thyroglobulin antibody in patients of cutaneous and oral lichen planus.
Aim: To study the prevalence of autoantibodies and the clinical spectrum of disease in an Indian patient subpopulation with lichen planus.
Methods: A cross-sectional epidemiological study comprising 100 lichen planus patients was conducted in the dermatology outpatient department of Seth G.S Medical College and King Edward Memorial Hospital, Mumbai, Maharashtra, India. Serum concentrations of circulating anti-nuclear antibodies, anti-desmoglein 1 antibody, anti-desmoglein 3 antibody, anti-keratinocyte antibodies, anti-mitochondrial antibodies and anti-thyroglobulin antibodies were determined by indirect immunofluorescence. Pairs of groups were compared using "Student's t-test" for normally distributed continuous data. The "χ2-test" was used for the categorical variables as needed. Statistical significance was set at P < 0.05.
Results: It was found that 65 (65%) patients showed the presence of at least one of the six autoantibodies that we studied, while 35 (35%) tested negative for all six of them. Positivity of anti-keratinocyte antibody in 26 (26%), anti-nuclear antibody in 22 (22%), anti-desmoglein 1 antibody in 19 (19%), anti-desmoglein 3 antibody in 16 (16%), anti-mitochondrial antibody in 9 (9%) and anti-thyroglobulin antibody in 6 (6%) patients was detected. It was observed that 55 (71.4%) patients of cutaneous lichen planus, 6 (46.1%) patients of mucosal lichen planus and 4 (40%) patients of cutaneous and mucosal lichen planus overlap showed presence of at least one autoantibody.
Conclusion: This study provides the serological parameters of a population of lichen planus from western India. Presence of autoantibodies in lichen planus suggests the possible role of humoral immunity in lichen planus. Identifying antibodies linked to lichen planus may help in identifying suitable diagnostic tests and therapeutic targets. Well-controlled studies with larger sample size are the need of the hour to confirm the role of humoral immunity in lichen planus.
Limitations: Studies with a larger number of patients as well as controls should be undertaken to further evaluate the role of autoantibodies in lichen planus.
Keywords: Anti-desmoglein 1 antibody; anti-desmoglein 3 antibody; anti-keratinocyte antibodies; anti-mitochondrial antibodies; anti-nuclear antibodies; anti-thyroglobulin antibodies; autoantibodies; lichen planus.