Oral Lichen Planus (OLP) is currently regarded as one of the potentially malignant diseases of the oral mucosa. OLP is a chronic and recurrent inflammatory autoimmune disorder [
1,
2]. Based on WHO, the criteria for OLP diagnosis include the existence of relatively symmetrical bilateral white reticular lesions that sometimes could be accompanied by erosive and/or atrophic lesions [
1,
3]. A meta-analysis in 2020 showed approximately 1.01% global prevalence for OLP that South America (1.74%) and North America (0.43%) had higher and lower prevalence, respectively [
2]. OLP mainly affects the buccal mucosa, tongue, and gums and appears in other places. The lesions represent bilaterally and frequently occur as a combination of clinical subtypes [
4]. The occurrence of OLP is more than the cutaneous form and is a treatment-resistant form of the disease [
5]. Adults aged 30 to 70 are more prone to OLP, especially affecting women [
6]. However, OLP rarely occurs in children, and most of the time, patients are unaware of their disease [
7]. According to the clinical manifestation, OLP is divided into different types such as reticular, erosive, popular, atrophic, plaque-like, and bullous [
8]. The reticular and erosive forms are the considerably common type of OLP [
9]. The investigations showed OLP increased the risk of oral squamous cell carcinoma. Therefore OLP is considered a potentially malignant disorder [
10,
11]. Between various types of OLP, the atrophic and erosive forms and plaque-like lesions on the back of the tongue have more malignant potential [
7]. Several studies indicate multiple factors such as dental materials, stress, genetics, liver diseases like Hepatitis C virus, smoking, and alcohol consumption can contribute to OLP [
7,
12,
13]. The etiology of OLP is undefined, but the hypotheses suggest that the immune system, specifically T cells, strongly correlates with OLP [
14].
Cytokines play a crucial role in OLP pathogenesis [
15]. Interleukin-8 (IL-8) is correlated with changes in the vital immune processes, for instance, chemotaxis and NETosis [
16]. In healthy tissues, the interleukin-8 concentration of tissues is minor. However, in response to pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-1, and bacterial infection, it rapidly increases from 10 to 100 fold base value [
17]. Interleukin-1 and TNF-a stimulate Keratinocytes, macrophages, T cells, endothelial cells, and fibroblasts which can cause the release of a considerable amount of IL-8 and raises the penetration of cytotoxic T cell in OLP lesions [
11]. The gene polymorphisms of interleukin-8 are associated with susceptibility to several diseases such as Behçet’s, multiple sclerosis, osteoarthritis, systemic lupus erythematosus nephritis, osteosarcoma, periodontitis, oral and different cancer types [
18‐
20]. Previous studies have revealed that interleukin-8 gene polymorphisms at positions − 251 and + 781 impacted interleukin-8 expression [
21]. Recently, the association of different polymorphisms of the IL-8 gene and other cytokines with the occurrence and severity of OLP has been reported [
22‐
25]. Therefore, the current study was designed to investigate the association of IL-8 + 781 SNP with the risk and severity of OLP disease in an Iranian population.