Establishment of a protein biochip to detect serum IgG antibodies against IL-2 and soluble CD25 in hemophagocytic lymphohistiocytosis

Abstract Background Interleukin-2 (IL-2) and soluble CD25 (sCD25) are among the most important cytokines and diagnostic biomarkers in hemophagocytic lymphohistiocytosis (HLH). Detecting serum level of IL-2 and sCD25 is valuable for making clinical diagnosis and treatment decision in HLH. Methods Since tests showing serum IgG antibody against IL-2 or sCD25 have never been carried out, a new protein biochip, which was modified with cysteine and activated sophorolipid (Cys-SL), was developed. Results Limits of detection on the biochip were 78 pg/ml for IL-2 and 39 pg/ml for sCD25, respectively. The data showed that on-chip seroimmunological responses to IL-2 and sCD25 proteins were 20.8% and 83.1% and the seroprevalence of IL-2 and sCD25 IgG antibodies were 45.5% and 57.2%, respectively. Data collection for the seroprevalence of serum antigen-antibody complex of sCD25 was 68.8%. The new biochip model shared similar sensitivity and specificity to chemiluminescent immunoassay (CLIA) in its measuring capacity of serum sCD25. Conclusions We addressed and confirmed the involvement of serum IgG antibodies against IL-2 and sCD25 as well as Ag-Ab complex of sCD25 in HLH patients. Therefore, this biochip platform would offer a new technological substitution for clinical serological diagnosis of HLH.