P<0.05 was considered statistically significant. Mean salivary exosomal and gingival PD-L1 mRNA expression in periodontitis patients were both approximately 10-fold higher than in control subjects (p < 0.001). Salivary and gingival PD-L1 mRNA levels were positively correlated (p < 0.001). High PD-L1 expression was associated with advanced periodontitis stage (p = 0.005). The gene discussed is CD274; the disease is periodontitis.