The Expression pattern of NK cells in systemic lupus erythematosus patients with different disease activities

Data demonstrated the role of natural killer (NK) cells in systemic lupus erythematosus (SLE). We aimed to determine the immunophenotype and frequency of NK cells and their subsets, CXCR3, CD161 expression in blood and renal tissue of SLE patients with and without lupus nephritis and their relationship with disease activity. The study included 31 SLE patients and 11 controls. Study participants underwent full history and thorough clinical examination. SLE patients underwent routine laboratory investigations. Renal tissue biopsies were taken from patients with lupus nephritis. The frequency of NK cell subsets in blood of patients and controls and renal tissue from patients was performed by flow cytometry. An increase in circulatory CD56bright NK cells and its CD56bright CD16dim subtype was associated with the severity of systemic manifestations in SLE patients. Total CD56bright NK cells and its CD56bright CD16bright subtypes in renal tissues were related to renal damage. We detected decreased CD161 expression on NK cells related to renal damage and severity of systemic manifestations in SLE patients. Decreased expression of CXCR3 on NK cell surface in renal tissues causes misdirected trafficking of NK cells that seems to reduce the severity of lupus nephritis. In conclusion, our results paved the way to understanding the role of NK cells in the pathogenesis of SLE which may represent a future target for immune therapy of SLE. NK and CD56dim subset were decreased in the blood and increased in renal tissue of SLE patients, while the CD56bright subset was increased in blood and decreased in renal tissue reflecting their effects on renal damage and severity of manifestations in SLE.