Quantitation of mHLA-DR and nCD64 by Flow Cytometry to Study Dysregulated Host Response: The Use of QuantiBRITE™ PE Beads and Its Stability

Quantitation of mHLA-DR and nCD64 is useful in understanding the dysregulated host response. The down regulation of HLA-DR expression on the circulating monocytes (mHLA-DR) is associated with anti-inflammatory response, and an increased expression of CD64 on neutrophil surface (nCD64) is associated with pro-inflammatory response. Quantitation of these antigen expression using beads (QuantiBRITE™ PE) is a precision technique. These beads are reported to be stable for 24 h after reconstitution. We report the results of our investigation examining the stability of QuantiBRITE PE beads over a period of 4-week post-reconstitution. The data suggest that reconstituted QuantiBRITE PE beads, if stored in dark at 2–8 °C, can be effectively used for up to 2 weeks for determining nCD64 and mHLA-DR antibody bound per cell (ABC) values.