Expression of soluble and membrane-bound programmed death protein 1 in psoriasis vulgaris patients: a case-controlled study

Background and aim Programmed cell death-1 (PD1) is an immunoreceptor that negatively regulates antigen receptor signaling and plays a critical role in the immunoregulation of autoimmune diseases. Objective The objective of this study was to assess both soluble programmed cell death-1 (sPD1) and membrane-bound PD1 levels in psoriatic patients, and to correlate them with disease severity. Patients and methods Twenty-one psoriatic patients and 20 age-matched and sex-matched controls were included. Full clinical examination was done and tissue and blood levels of PD1 were measured by enzyme-linked immunosorbent assay. Results Levels of sPD1 were significantly lower in patients than in controls (P 0.001). Regarding the level of tissue PD1, it was lower in psoriatic skin biopsies (0.32 ± 0.22) than in controls (0.54 ± 0.08); however, this difference was not statistically significant (P =0.89). A statistically significant positive correlation was found between tissue and sPD1 levels (P= 0.02, r=0.5), and a significant negative correlation with the extent of the disease (P =0.024, r= −0.5). Conclusion Psoriatic patients have significantly lower sPD1 level. PD1 might play an important role in the pathogenesis of psoriasis vulgaris.