PD-L1-expressing neutrophils as a novel indicator to assess disease activity and severity of systemic lupus erythematosus

It is well-known that increased frequency of neutrophils was found in patients with systemic lupus erythematosus (SLE). However, the immunomodulatory roles and mechanisms of neutrophils in SLE are poorly understood. Patients with SLE were recruited from the First Affiliated Hospital of Nanchang University. The medical history, clinical manifestations, physical examination, laboratory measurements, therapeutic regimen and treatment response were recorded. The expression of costimulatory molecules including programmed death 1 (PD-1), programmed death ligand 1 (PD-L1), T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3), CD40, T cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory domains (TIGIT), CD80 and CD86 on neutrophils were determined by flow cytometry. The frequencies of PD-L1-expressing neutrophils in patients with SLE were further analyzed for their correlation with markers of autoimmune response, inflammation, disease activity and severity of SLE. The frequency of PD-L1-expressing neutrophils was significantly elevated in SLE patients compared to the healthy controls (P