J Cosmet Dermatol. 2020;00:1–4. wileyonlinelibrary.com/journal/jocd | 1 © 2020 Wiley Periodicals LLC 1 | INTRODUCTION Lichen planus (LP) is an auto-inflammatory skin disorder. While it is not known the exact etiology of LP, a retarded hypersensitivity response can play its part. 1 Lymphocytic infiltration (T lympho- cytes), and macrophages in the basal lamina, leading to the pro- duction of inflammatory mediators is a typical characteristic of LP. The cytotoxic activity of T lymphocytes is considered to be a useful marker for neopterin. 2 After IFN-β stimulation, standard Th1-cytokine preferentially generates and releases large amounts of neopterin synthesized by GTP-cyclohydrolase I from guanosine triphosphate (GTP). 3 The absence of its biological activity together with a half-life (T1/2) fully determined by its glomerular filtration function means that a raised level of neopterin reflects the effect of the INF γ modulating action. 4 Neopterin levels reflect the stage of activa- tion of the cellular immune system, which is of importance in the pathogenesis and progression of various diseases, for example in viral infections, 5 in autoimmune or inflammatory diseases, rejec- tion episodes following allograft transplantation, and in several Received: 21 December 2019 | Revised: 23 March 2020 | Accepted: 26 March 2020 DOI: 10.1111/jocd.13417 ORIGINAL CONTRIBUTION Assessment of neopterin level and severity in lichen planus patients treated with narrow-band ultraviolet B Fathia M. Khattab MD | Mai A. Samir MD Department of Dermatology, Venereology, and Andrology, Faculty of Medicine, Zagazig University, Zagazig, Egypt Correspondence Fathia M. Khattab, Department of Dermatology, Venereology and Andrology, Faculty of Medicine, Zagazig University, Zagazig, Egypt. Email: fathiakhattab@yahoo.com Abstract Background: Neopterin is a cellular immunity biochemical marker. Serum and saliva neopterin levels have been reported to increase in lichen Planus. Nonetheless, analy- sis has not yet been made for the direct link between narrow band ultraviolet B and severity of Lichen planus. Aim: We aimed to assess serum neopterin levels in patients who receive narrow band ultraviolet B therapy treatment with lichen planus, paired with the severity of the disease. Patients and Methods: The study consisted of 35 lichen planus patients and 30 healthy individuals. A 35 patient group received narrow band ultraviolet B therapy. An enzyme-related immunosorbent assay procedure was used in serum neopterin analysis before and post-therapy. Results: The correlation between the level and severity of the patient group was statistically significant (P = .001). In patients with severe disease, serum neopterin levels were significantly increased. Also, in the severe lichen planus group, the serum neopterin level was statistically higher than that of the mild or moderate groups (P = .001).Also, a significant decrease was seen following therapy according to serum neopterin level. Conclusion: Serum neopterin levels are a useful marker for the assessment of the severity and effectiveness of narrow band ultraviolet therapy. Thus, our findings may provide a new approach with the management of disease and follow-up strategies in patients with lichen planus. KEYWORDS lichen planus, narrow-band ultraviolet B, neopterin