Relationship of systemic lupus erythematosus disease activity to circulating apoptotic neutrophils as detected with annexin v

Abstract EN

Background : systemic lupus erythematous (SLE) is an autoimmune disorder characterized by defective phagocytosis, increased apoptotic leukocytes and presence of autoantibodies in the serum.

Rheumatoid arthritis (RA) is another autoimmune disorder, which is also characterized by the presence of autoantibodies.

Annexing V is a member of the annexing family that binds phospholipids in a calcium dependent manner.

This is the basis for using annexing V as a tool to monitor cell membrane anomalies including apoptosis.

Objective : To quantify the percentage of apoptotic peripheral blood neutrophils in SLE patients with flowcytometry using annexing V and to determine their relations with neutropenia, anti-annexing V autoantibodies and disease activity.

Methodology : Neutrophil apoptosis in SLE patients (n = 31) was assessed with flowcytometry (FCM) using annexing V binding.

Age and sex matched RA patients (n = 27) were tested as disease control and 15 age and sex matching apparently healthy individuals were included as controls.

Results : The percentage of apoptotic neutrophils as detected both with annexing V binding and with morphology was increased in peripheral blood of SLE patients (3.70 ± 0.73 and 2.89 ± 0.65) as compared with disease controls (1.59 ± 0.89 and 1.41 ± 0.59) and healthy controls (1.17 ± 0.40 and 1.49 ± 0.58) respectively.

Total autoannexin V antibodies was increased in the serum of SLE patients (358.56 ± 148.59) in comparison to disease and healthy controls (11.72 ± 2.96 and 10.33 ± 1.45) respectively.

A non-significant correlation was found between apoptotic cells as detected with morphology and those detected with annexing V binding in any of the studied groups (r = 0.162, 0.085 and 0.103 for healthy controls, disease controls and SLE patients respectively).

SLE neutrophil apoptosis correlated positively with neutropenia and disease activity as assessed with Systemic Lupus Activity Measurement (SLAM) score.

SLE neutrophil apoptosis also correlated negatively with the presence of anti-annexing V antibodies.

Meanwhile, neutrophil apoptosis did not show significant correlation with neither neutropenia, level of autoantibodies to annexing V nor with disease activity in RA patients.

Conclusion : increased circulating apoptotic neutrophils in SLE correlate positively with neutropenia and disease activity (SLAM).