Interleukin-8 Predicts Fatal Kala-Azar: A Case-Control Study

Area of Science:

• Immunology
• Tropical Medicine
• Biomarker Discovery

Background:

• Kala-azar (visceral leishmaniasis) presents significant mortality risks, particularly in endemic regions.
• Early identification of biomarkers is crucial for timely intervention and risk stratification.
• Serum cytokines are potential indicators of disease severity and prognosis.

Purpose of the Study:

• To identify serum cytokine profiles that predict fatal outcomes in kala-azar patients.
• To evaluate specific cytokines, including IL-1β, IL-6, IL-8, IL-10, IL-12, and TNF-α, as prognostic biomarkers.
• To establish a reliable predictive threshold for mortality using identified biomarkers.

Main Methods:

• Comparison of serum cytokine levels between 48 deceased kala-azar patients and 42 survivors.
• Quantification of cytokines using flow cytometry.
• Statistical analysis including Wilcoxon rank-sum test and Receiver Operating Characteristic (ROC) analysis with Youden's index.

Main Results:

• Significantly higher Interleukin-8 (IL-8) concentrations were observed in deceased patients (median 76.5 pg/mL) compared to survivors (median 26.4 pg/mL; p < 0.0001).
• ROC analysis determined an optimal IL-8 cutoff of 49.3 pg/mL, with a clinical threshold of 50 pg/mL.
• An IL-8 level ≥ 50 pg/mL predicted fatal kala-azar with 70.8% sensitivity and 76.2% specificity (AUC 0.75).
• Other tested cytokines (IL-1β, IL-6, IL-10, IL-12, TNF-α) did not show significant prognostic value.

Conclusions:

• Serum IL-8 levels ≥ 50 pg/mL serve as a reliable predictor of fatal kala-azar.
• IL-8 emerges as a valuable prognostic biomarker for identifying high-risk patients.
• This finding can aid in early risk stratification and targeted management strategies for kala-azar.