Natural Killer Cell Count in Systemic Lupus Erythematosus Patients: A Flow Cytometry-Based Study

Area of Science:

• Immunology
• Autoimmune Diseases

Background:

• Natural killer (NK) cells are crucial innate immune mediators involved in adaptive immune system regulation.
• Previous research indicates a role for NK cells in immune system modulation.

Purpose of the Study:

• To investigate and compare NK cell counts in patients diagnosed with systemic lupus erythematosus (SLE) against a control group of healthy individuals.

Main Methods:

• Flow cytometry was utilized to identify and quantify NK cells (CD3(-) cells) and their subsets (CD56(+) and CD16(+)) in 32 SLE patients and 30 healthy controls.
• Safety of Estrogens in Lupus Erythematosus National Assessment SLE Disease Activity Index (SELENA-SLEDAI) scores were assessed.
• Receiver Operating Characteristic (ROC) curve analysis was performed to establish cut-off values for NK cell populations.

Main Results:

• SLE patients exhibited significantly lower percentages of CD3(-) NK cells (12.35%), CD56(+) NK cells (18.7%), and CD16(+) NK cells (46.6%) compared to controls (24.67% and 46.6%, respectively; p<0.001).
• ROC analysis identified specific cut-off values for CD3(-), CD56(+), and CD16(+) NK cells with high sensitivity and specificity in distinguishing SLE patients.
• No significant association was found between NK cell subsets and clinicopathological parameters such as age, sex, disease activity, autoantibodies (ANA, dsDNA), lymphocyte count, or renal involvement.

Conclusions:

• NK cells, including their CD56(+) and CD16(+) subpopulations, are demonstrably decreased in individuals with SLE.
• The findings suggest a potential role for reduced NK cell counts in the immunopathogenesis of SLE.