Optimization and performance of the protocol. A: Selection of storage buffer for sorted cells. RNA yield from 15,000 N tonsil cells. The cells were sorted into different storage reagents and mRNA was purified with MBI either immediately after cell sorting or after 14 days of storage at 4°C, -20°C and -80°C. RNA yields were determined by RT-qPCR targeting PPIA. Mean Cq values were calculated from triplicate RNA extractions from each storage reagent. Error bars represent SD (n = 3). B: Amplified cDNA yield from a fixed number of flow sorted N and PB cells derived from a tonsil. The cells were sorted in lysis/binding buffer and mRNA was purified with MBI. Prior to amplification, the mRNA was concentrated by speedVac centrifugation. The amplified cDNA yield was measured on the nanodrop. Error bars represent SD of 3 experiments.