Multiple Cytokine Analysis in Human Tears: An Optimized Procedure for Cytometric Bead-Based Assay

Abstract

PURPOSE: To compare instruments and reagents used for cytometric bead-based assay (CBA) of cytokines in human tears. METHODS: Two CBA instruments and reagent kits from five vendors were compared in parallel. Vendor protocols were modified to accommodate tear volumes. Precision, recovery, dilution linearity, and stability were evaluated. RESULTS: Luminextrade mark and Bio-Radtrade mark proved optimal for tear CBA. Good correlation for dilution linearity was observed (r > 0.80, p < 0.05) for 1-4-mu l sample volumes. Samples were stable for 30 min at 25 degrees C. CONCLUSION: Many tear cytokines can be reliably measured by CBA using an optimized protocol. Concentrations remain stable during periods consistent with collection.