To assess whether automated white blood cell inflammatory parameters (WBC-IP), particularly immature granulocyte percentage (IG%), distinguish active childhood-onset systemic lupus erythematosus (SLE) from remission and track disease activity.
Approach:
Study design and participants: Prospective, single-center study of 74 children with SLE (43 with active disease and 31 in remission) and 112 age-matched healthy controls.
Measurements: Researchers measured WBC-IP with a Sysmex XN-9000 analyzer and assessed associations with SLEDAI-2K, clinical SLEDAI-2K, and physician global assessment. Active-disease participants were assessed at enrollment, 4–6 weeks later, and upon reaching inactive disea…
Key Findings:
IG% had the highest discriminatory performance among the evaluated WBC-IP for active disease versus remission (AUC 0.90), comparable to ESR (AUC 0.92); the difference was not statistically significant.
At an IG% cutoff above 0.35%, sensitivity was 81%, specificity 87%, and accuracy 84%. Median IG% was 0.9% in active disease and 0.2% in both remission and healthy controls.
IG% was moderately correlated with disease activity measures, while conventional markers showed stronger correlations; complement C3 had the strongest inverse correlations.
During follow-up, median SLEDAI-2K declined from 14 at enrollment to 8 at 4–6 weeks and 2 at inactive disease. IG% rose from 0.9% to 2.3% before declining to 0.5%.
Interpretation:
The authors described WBC-IP, particularly IG%, as potential complementary biomarkers for assessing disease activity in children with SLE, not replacements for established laboratory markers or clinical assessments. They noted that treatment-related changes may complicate interpretation of longitudinal WBC-IP.
Limitations:
Small sample size and single-center design, with no independent validation.
The IG% cutoff was derived and evaluated in the same cohort, potentially overestimating performance.
Treatment-related hematologic changes may have affected longitudinal measurements, and subclinical infections could not be completely excluded.
Established pediatric reference ranges for WBC-IP were unavailable.
Conclusion:
The authors called for larger multicenter studies to validate the findings and clarify how treatment affects these parameters.
