library_construction_protocol: Mice were euthanized and auricular LNs were disected.                     Lymph nodes were digested in IMDM containing 100µg/mL Liberase TL and 100µg/mL                     DNase I for 20 minutes at 37°C. In the last 5 minutes of incubation, EDTA was                     added at a final concentration of 10mM. Cells were collected, filtered through a                     70µm cell strainer, washed with IMDM and maintained strictly at 4°C. Cells were                     stained with FACS antibodies, then sorted into 384-well plates Single-cell                     RNA-seq libraries were prepared as previously described {Jaitin, 2014}. In                     brief, mRNA from single cells sorted into capture plates were barcoded and                     converted into cDNA and then pooled using an automated pipeline. The pooled                     sample was linearly amplified by T7 in vitro transcription, and the resulting                     RNA was fragmented and converted into a sequencing-ready library by tagging the                     samples with pool barcodes and Illumina sequences during ligation, RT, and PCR.                     Each pool of cells was tested for library quality and concentration as described                     previously {Jaitin, 2014}