Blood soluble CD89-IgA complex may be a potential biomarker for predicting multi-organ involvement, especially renal involvement in children with immunoglobulin A vasculitis.

• Soluble CD89-IgA complex (sCD89-IgA) as a type of IgA immune complexes is associated with renal involvement in IgAV. • However, the ability of blood sCD89-IgA as a biomarker to predict renal involvement or multi-organ involvement in children with IgAV is not clear. • We conducted the first study of the relationship between blood sCD89-IgA levels and multiple organs involvement in pediatric IgAV patients, this is of great significance for the study of IgAV or IgAVN in children. Immunoglobulin A vasculitis (IgAV) is a kind of systemic vasculitis mediated by IgA immune complexes (IgA-ICs). Soluble CD89-IgA complex (sCD89-IgA) as a type of IgA-IC associated with renal involvement in IgAV, the ability of blood sCD89-IgA as a biomarker to predict renal or multi-organ involvement in children with IgAV is not evident, and this study mainly focused on this. The clinical characteristics and blood samples of 57 pediatric patients with IgAV were collected. ELISA was used to detect plasma IgA-ICs and sCD89-IgA levels. Serum IgA levels were detected by Nephelometry method. Statistical analysis was conducted to analyze the relationship between sex, age, serum IgA levels, plasma IgA-ICs levels, plasma sCD89-IgA levels and the involvement of multiple organs (except skin) including kidneys in these patients. Compared to patients with simple skin involvement, patients with multi-organ involvement, especially kidneys, had higher levels of plasma IgA-ICs and sCD89-IgA, and the statistical difference was significant. In addition, a high level of plasma sCD89-IgA was a high-risk factor for patients to develop multi-organ or renal involvement in addition to the skin. ROC curve analysis showed that the AUC was 0.861 (Sensitivity: 83 %, Specificity: 88 %, p < 0.0001) when plasma sCD89-IgA predicted multi-organ involvement, and AUC 0.926 (Sensitivity: 94 %, Specificity: 88 %, p < 0.0001) for predicting renal involvement. The results suggested that plasma sCD89-IgA may be a potential biomarker for predicting multi-organ involvement (in addition to skin), especially renal involvement in IgAV pediatric patients. [ABSTRACT FROM AUTHOR]