The phenotype of CD3–CD56bright and CD3–CD56dim natural killer cells in systemic lupus erythematosus patients and its relation to disease activity

Abstract

Introduction: Systemic lupus erythematosus (SLE) patients have decreased natural killer (NK) cell counts. The decrease in the number of NK cells has implications for a decrease in the function of NK cells which can affect the progression of SLE disease. The study aim was to determine profiles of CD3-CD56 bright and CD3-CD56 dim NK cells in SLE patients and their relation to disease activity. Material and methods: This study included 36 patients of SLE who fulfilled the ACR 1997/SLICC 2012 criteria, women aged 18-49 years. Disease activity was assessed by the Mex-SLEDAI. Peripheral blood samples from SLE patients were analyzed by flow cytometry to evaluate NK cell subsets, according to differential expression of the main subset of NK cells, which is CD3-CD56 bright and CD3-CD56 dim . Results: The mean percentage of regulatory NK cell count (CD3-CD56 bright ) in active SLE patients was significantly lower (p = 0.000) than in inactive SLE patients. The mean percentage of cytotoxic NK cell count (CD3-CD56 dim ) in active SLE patients was significantly (p = 0.000) higher than in inactive SLE patients. A correlation was observed between two subsets of NK cells with disease activity (p = 0.00). The percentage of CD3-CD56 bright NK cells was negatively correlated with disease activity (r = -0.766), whereas the percentage of CD3-CD56 dim NK cells positively correlated with disease activity (r = 0.761). Conclusions: There is a difference in the mean percentage of the number of NK cells (CD3-CD56+) in both a subset of regulatory NK cells (CD3-CD56 bright ) and cytotoxic NK cells (CD3-CD56 dim ) in active and inactive SLE patients and it is closely related to SLE disease activity.