Simultaneous detection of platelet-specific antibodies based on a photonic crystal-encoded suspension array.

BACKGROUND:The appearance of antibodies to platelets in the blood is an important cause of immune thrombocytopenia (ITP), and platelet glycoprotein (GP)-specific antibody detection may be helpful to diagnose this condition. METHODS:Photonic crystal microspheres with different distinct reflection spectra were coated with anti-GPIIb, -GPIIIa, -GPIb and -GPIX monoclonal antibodies (MoAbs) to create a photonic crystal-encoded suspension array (PCSA). Fluorescein isothiocyanate-labelled goat anti-human IgG was added to detect human IgG simultaneously. The detection results were analysed by fluorescence microscopy. Parallel MoAb immobilization of platelet antigen (MAIPA) was used as a reference test. Both methods were used to analyse 63 clinical samples including serum from 32 ITP patients and 31 healthy humans. RESULTS:The PCSA showed greater sensitivity than MAIPA in detecting anti-GPIIb (75.0% vs 31.1%) and GPIIIa (84.4% vs 40.6%) antibodies and similar sensitivity as MAIPA in detecting anti-GPIb (37.5% vs 34.4%) and GPIX (50.0% vs 40.8%) antibodies. The MAIPA and PCSA tests had similar specificity. The PCSA detected higher dilutions of serum containing anti-GPIIIa antibody or anti-GPIIb antibody than did MAIPA. The entire testing process was controlled within 3.5h. CONCLUSIONS:The PCSA assay described has comparable or better sensitivity and specificity compared to the MAIPA and is more rapid.